AQA GCSE PHYSICS ►.

AQA GCSE PHYSICS ►

Main Contents ► Use arrow keys to advance within a slide Electricity
Cost Charge Control Mains Graphs Energy Acceleration Voltage Friction Electricity Forces Moments Structure Types Radioactivity Momentum PHYSICS Circular Induction Waves Characteristics Energy Electromagnetism Electromagnetic Work Optical Space Sound Resources Seismic Efficiency Tectonic Thermal Universe Solar Extras: Electricity, Forces, Waves, Space, Energy, Radioactivity, Links, Terms, Physics Click on this bar to return to this slide

1 Electricity ► Idea map Atom Electron Proton Neutron Moving
Stationary Current Charge Voltage Energy Mains Control Cost

Electricity ► Voltage ► Idea map
1.1 Energy Electrons causes... Voltage Current Circuit Series Parallel Components Ammeter Voltmeter Thermistor LDR

Electricity ► Voltage ► Energy and Electrons
Electricity is fundamentally about 2 things… Energy Ability to do Invisible Electrons Tiny particle Carry charge Carry Energy Effectively Invisible

Electricity ► Voltage ► Current
Electric Current Current Flow of charge Electricity Moving Electrons Symbol I Mean the same Small Current Large Current

Electricity ► Voltage ► Amps
The current flowing through a component in a circuit is measured in amperes (A). An ammeter is connected in series with the component. 1 Amp = 6 billion billion electrons per second

Electricity ► Voltage ► Voltage Idea
Energy per electron Voltage Potential Energy Potential Symbol V Mean the same High Voltage Low Voltage Low energy Electron High energy Electron

Electricity ► Voltage ► Potential Difference
Potential Energy Difference between 2 points on a wire Potential Difference P.D. Difference in Voltage Voltage across Mean the same Energy

Electricity ► Voltage ► Voltmeter
4 Volts The p.d. across a component in a circuit is measured in volts (V) A voltmeter connected across (in parallel with) the component.

Electricity ► Voltage ► Relationship Concept
The next four slides make essentially the same point about the relationship between current and voltage… Relationship Proportional Connection One can be worked out from the other One causes a change in the other Link A formula allows us to calculate a value Dependent Mean the same

Electricity ► Voltage ► Voltage needed
A current will flow through an electrical component (or device)… Only if there is a voltage or potential difference (p.d.) across its ends.

Electricity ► Voltage ► More voltage, more current
The bigger the potential difference across a component… The bigger the current that flows through it.

Electricity ► Voltage ► Graphing Relationship
Current Proportional : As one value increases so does a second value Voltage Current-voltage graphs are used to show how the… Current through a component varies with the voltage across it.

Electricity ► Voltage ► V = I R
The current through a resistor (at constant temperature) is proportional to the voltage across the resistor. Voltage = Current x Resistance V I R 10 Volts 2 Amps 5 Ohms

Electricity ► Voltage ► Series Circuit
2 Ω 4 Ω When components are connected in series: Their total resistance is the sum of their separate resistances. The same current flows through each component. The total potential difference of the supply is shared between them

Electricity ► Voltage ► Parallel Circuit
When components are connected in parallel: The current in the branches equals that leaving the battery The current may vary from branch to branch The total potential difference of the supply is same for each branch

Electricity ► Voltage ► Filament Bulb
Resistance Temperature The resistance of a filament lamp increases… As the temperature of the filament increases.

Electricity ► Voltage ► Diode
CURRENT normal flow VOLTAGE no flow The current through a diode flows in one direction only. The diode has a very high resistance in the reverse direction.

Electricity ► Voltage ► Light Dependent Resistor
1000 Ω 10 Ω Could be called “darkness dependent resistor” The resistance of a light dependent resistor decreases… As the light intensity increases. It resists when it is dark…

Electricity ► Voltage ► Thermistor
1000 Ω 10 Ω A “coldness dependent resistor” The resistance of a thermistor decreases… As the temperature increases. Resists when it is cold

Electricity ► Voltage ► Symbols
Cell Switch (open) Battery Switch (closed) Variable resistor L.D.R Diode Fuse A Resistor V Ammeter Lamp Thermistor Voltmeter

Electricity ► Energy ► Ideas map
1.2 Electrons Coulomb deliver… in a certain… Energy (J) Time (s) to give us… Power Watt (J per s) Voltage x Current

Electricity ► Energy ► Electrons carries energy
10 J £20 This is an electron It collects energy at the battery… Travels around a circuit… And delivers it to a component

Electricity ► Energy ► Electrons deliver Energy
£30 30 J Bank Shop Shop 20 J 10 J £20 £10 As an electric current flows through a circuit, energy is transferred The energy is transferred from the battery or power supply… …to the components in the electrical circuit.

Electricity ► Energy ► Heat from a wire
When Charge flows through a resistor, electrical energy is transferred as heat.

Electricity ► Energy ► Energy per Time
£10 £10 10 J 10 J

Electricity ► Energy ► Power
Power is energy transferred per second Power is measured in Joules per Second known as a Watt 1 Watt = 1 J of energy in 1s 10 J 10 J Power = Current x Potential Difference P I V 10 Watts 2 Amp 5 Volt

Electricity ► Energy ► Coulomb
Seconds are inconveniently small to measure the age of a person. We use a word which means 31,536,000 seconds. The word is year. 1km 2 cubic kilometres contain about 6 billion billion grains of salt Electrons are inconveniently small to measure everyday numbers of electrons. We use a word which means 6,000,000,000,000,000,000 electrons The word is Coulomb.

Electricity ► Energy ► E = VQ
50 J 50 J The higher the voltage of a supply… the greater the amount of energy transferred for… a given amount of charge which flows. Energy = Potential Difference x Charge E V Q 10 Joules 5 Volts 2 Coulombs

Electricity ► Energy ► Q = I t
3 Coulombs / Sec (3 Amps) …For 5 Seconds… Equals 15 Coulombs Charge = Current x Time Q I t 15 Coulombs 3 Amps 5 seconds

Electricity ► Energy ► Table of 7 key ideas
DESCRIPTION NAME SYMBOL UNIT Ability to do Energy E Joule (J) Electrons Charge Q Coulomb (C) Change Time t Second (s) Charge per Time Current I Amp (A) Energy per Charge Voltage V Volt (V) Energy per Time Power P Watt (W) Obstacle Resistance R Ohm (Ώ)

Electricity ► Energy ► 7 ideas connected
1 . V = I R E = V Q E = P t Q = I T P = I V V I E Q t P

Electricity ► Mains ► Ideas map
1.3 Types of Current Direct Alternating Mains Plug Safety Live Neutral Earth Fuse Circuit Breaker

Electricity ► Mains ► Mains voltage
The UK mains supply is about 230 volts. Mains can kill if it is not used safely.

Electricity ► Mains ► Plug
Earth pin Copper Core Plastic Layer Fuse Live pin Plastic Case Neutral Pin Cable grip Brass Pins and Copper Wires are conductors, plastic is an insulator

Electricity ► Mains ► Alternating Current
An alternating current (a.c.) is one which is constantly changing direction. Mains is an a.c. supply. In the UK it has a frequency of 50 cycles per second or 50 hertz (Hz) which means that it changes direction and back again 50 times each second.

Electricity ► Mains ► Direct Current
Cells and batteries supply a current which always flows in the same direction. This is called a direct current (d.c.).

Electricity ► Mains ► Oscilloscope Trace
d.c. Candidates should be able to compare the voltages of d.c. supplies… And the frequencies and peak voltages of a.c. supplies from diagrams of oscilloscope traces.

Electricity ► Mains ► Safety
If a fault in an electrical circuit or an appliance causes too great a current to flow, the circuit is switched off by a fuse or a circuit breaker.

Electricity ► Mains ► Fuse
Normal Fault 12 A 14 A Fuse : 13 A Fuse : 13 A When the current through a fuse wire exceeds the current rating of the fuse.. The wire becomes hot and will (eventually) melt breaking the circuit and switching off the current.

Electricity ► Mains ► Fuse selection
13 Melts too late The Goldilocks and the Three Bears Theory of Fuse Selection™ 10 Just right 5 Melts too soon 3 2 Safe Dangerous The fuse should have a value higher than, but as close as possible to, the current through the appliance when it is working normally. The manufacturer will normally recommend a fuse.

Electricity ► Mains ► Circuit Breaker
Normal Fault Strong Magnetic Force Weak Magnetic Force High Current Safe Current A circuit breaker uses an electromagnet to detect a surge and operate a very quick automatic off switch. When the fault is fixed the circuit breaker can be reset.

Electricity ► Mains ► Earth Wire
No Earth Wire Earth Wire Exposed Wire Appliances with metal cases need to be earthed. The earth pin is connected to the case via the yellow/green wire. If a fault in the appliance connects the case to the live wire, and the supply is switched on, a very large current flows to earth and overloads the fuse.

Electricity ► Mains ► Live Wire
The live terminal of the mains supply alternates between a positive and negative voltage with respect to the neutral terminal. The neutral terminal stays at a voltage close to zero with respect to earth.

Electricity ► Charge ► Idea Map
1.5 Electrons & Protons Extra Electrons Equal Lack of Electrons Negative Neutral Positive Force Force Attraction Uses Photocopier Electrolysis Printer

Electricity ► Charge ► Balance of Protons and Electrons
- - Protons + - + - + + - + - + + - + - + - Extra Electrons Equal Lack of Electrons Negative Neutral Positive

Electricity ► Charge ► Multiple Terms
Property of Electrons and Protons Particles which can exert a force Ability to create movement Mean the same Stationary Electrons Electrostatics Static Electricity Static Trillions of Electrons ‘flooding in’ Trillions of Electrons leaving an area The balance between Electrons and Protons Mean the same Negatively Charged: Extra Electrons Positively Charged: Electrons missing Both Electrically Charged

Electricity ► Charge ► Phenomena
When certain different insulating materials are rubbed against each other they become electrically charged. Electrically charged objects attract small objects placed near to them.

Electricity ► Charge ► Charges cause Repulsion and Attraction
+ - + - + - + - When two electrically charged objects are brought close together, they exert a force on each other. These observations can be explained in terms of two types of charge called positive (+) and negative (-). Two objects which have the same type of charge repel. Two objects which have different types of charge attract.

Electricity ► Charge ► Charge is conserved
Neutral Positive Neutral Negative + + - - - - - - - + - - + - + + + + + + - + - + - + + - + + + + + + + + - - - - - - - + - - - - + - + + + + - - - - + - + - + + + + - - - - - - + - + + + - + + When two different materials are rubbed against each other, electrons, which have a negative charge, are rubbed off one material on to the other. The material which gains electrons becomes negatively charged. the material which loses electrons is left with an equal positive charge.

Electricity ► Charge ► Discharge
A charged conductor can be discharged by connecting it to earth with a conductor.

Electricity ► Charge ► Sparks
The greater the charge on an isolated object, the greater the voltage (potential difference) between the object and earth. If the voltage becomes high enough, a spark may jump across the gap between the object and any earthed conductor which is brought near it.

Electricity ► Charge ► Safety
Refuelling can be dangerous because a spark could ignite the fumes. A wire is used to conduct the electrostatic charge away safely (discharging).

Electricity ► Charge ► Metal
Metals are good conductors of electricity because some of the electrons from their atoms can move freely throughout the metal structure.

Electricity ► Charge ► Photocopier
Copying plate is electrically charged. An image of the page you want to copy is projected on to the plate. Where light falls on the plate, the Charge leaks away. The parts of the plate that are still charged attract bits of black powder. The black powder is transferred from the plate to a sheet of paper. The paper is heated to make the black powder stick. There is now a copy of the original page. A A

Electricity ► Charge ► Electrolysis
In solid conductors, an electric current is a flow of electrons. When some chemical compounds are melted or dissolved in water they conduct electricity. These compounds are made up of electrically charged particles called ions. The current is due to negatively charged ions moving to the positive terminal (electrode) and the positively charged ions moving to the negative electrode. Simpler substances are released at the terminals (electrodes). This process is called electrolysis.

Electricity ► Charge ► Electrolysis Deposition
1 amp 1 min 2 amps 1 min 2 amps 2 min During electrolysis the mass and/or volume of the substance deposited or released at the electrode increases in proportion to: The current. The time for which the current flows.

Electricity ► Control ► Ideas Map
1.6 Sensor Capacitor Variable Resistor Modifiers Potential Divider Relay Switches Transistor Logic Gates Processor Time Delay AND, OR, NOT Output device

Electricity ► Control ► Electronic Systems
Electronic systems have: Input sensors which detect changes in the environment. A processor which decides what action is needed. An output device creates a signal or action.

Electricity ► Control ► Input Sensors
Input sensors include: Thermistors which detect changes in temperature LDRs which detect changes in light Switches which respond to pressure, tilt, magnetic fields or moisture.

Electricity ► Control ► Output Devices
M Output devices include: Lamps and LEDs (light emitting diode) which produce light Buzzers which produce sound Motors which produce movement Heaters which produce heat

Electricity ► Control ► Variable Resistor
The flow of electricity through a circuit (the current) can be controlled by using a fixed or a variable resistor.

Electricity ► Control ► Potential Divider
POTENTIAL ENERGY Thermistor Variable Resistor V out V in The voltage that is supplied to the potential divider V in …. is shared across the two resistors. If either resistance is increased (or reduced), the share of the voltage across it also increases (or reduces).

Electricity ► Control ► Equal Resistance
5000 Ω 5 V 4000 Ω 4 V 3000 Ω 3 V 2000 Ω 2 V 1000 Ω 1 V Vout 0 Ω 0 V If the two resistors change by the same amount.. They will continue to share the voltage equally

Electricity ► Control ► Unequal Resistance
5000 Ω 5 V 4000 Ω 4 V 3000 Ω 3 V 2000 Ω 2 V 1000 Ω 1 V Vout 0 Ω 0 V It is the proportion of the resistance that is important. Here the variable resistor setting affects V out.

2 Forces ► Idea Map Friction Gravity Contact Field Muscular Magnetism
Balanced Unbalanced Around Pivot 90o to Motion No Acceleration Acceleration Moments Circular Constant Velocity Changing Velocity Graphs Momentum Mass

Forces ► Graphs ► Summary
2.1 Graphs Distance Velocity Stop Constant Velocity Greater Acceleration Faster Constant Velocity Velocity (m/s) Distance (m) Constant Velocity Acceleration Stop Time Time

Forces ► Graphs ► Distance Time
= Speed x Time d s t 24 km 6 km/h 4 hours

Forces ► Graphs ► Distance II
On a distance-time graph : Stationary objects are represented by horizontal lines Objects moving with a steady speed are represented by sloping straight lines. The steeper the slope of the graph, the greater the speed it represents. If an object moves in a straight line, how far it is from a certain point can be represented by a distance-time graph. Time Faster Constant Velocity Constant Velocity Distance (m) Stationary Stationary Faster Constant Velocity Constant Velocity

Forces ► Graphs ► Velocity
Speed: Constant Direction: Constant Velocity : Constant Speed: Constant Direction: Changing Velocity : Changing The velocity of an object is its speed in a given direction.

Forces ► Graphs ► Velocity Time
Velocity-time graphs can represent the motion of a body. The steeper the slope of the graph, the greater the acceleration it represents Constant velocity it is represented by a horizontal line. Constant acceleration it is represent by a straight sloping line..

Forces ► Graphs ►Acceleration
Time Velocity Change VELOCITY TIME The acceleration of an object is the rate at which its velocity changes. For objects moving in a straight line with a steady acceleration, the acceleration, the change in velocity and the time taken for the change are related as shown: Velocity Change = Acceleration x Time v - u a t 10 m/s 2 m/s2 5 seconds

Forces ► Graphs ► Gradient for Speed
100 km 2 hr 100 km ÷ 2 hr = 50 km/h DISTANCE TIME Candidates should be able to calculate the gradient / slope of a distance-time graph.

Forces ► Graphs ► Gradient for Acceleration
60 m/s 20 sec 60 m/s ÷ 20 sec = 3 m/s2 VELOCITY TIME Candidates should be able to calculate: The gradient of a velocity-time graph and interpret this as acceleration.

Forces ► Graphs ► Area for Distance
6 m/s 6 m/s 30m 15m VELOCITY VELOCITY 5 sec 5 sec The area under a velocity-time graph. for an object moving with constant acceleration represents distance travelled.

Forces ► Acceleration ► Ideas Map
2.2 Forces Newton Balanced Unbalanced Constant Velocity Acceleration F = ma eg 0 m/s or 10 m/s eg 2 m/s2 or 9 m/s2

Forces ► Acceleration ► Horizontal
Speed Direction No ? Acceleration Speed Direction Yes ?

Forces ► Acceleration ► Vertical
Speed Direction No ? Acceleration Speed Direction Yes ?

Forces ► Acceleration ► Constant Motion
STOP Balanced: 0 km/h Balanced: 60 km/h Balanced forces will have no effect on the movement of an object: It will remain stationary or, If it is already moving it will continue to move at the same speed and in the same direction.

Forces ► Acceleration ► Balanced Forces
The forces acting on an object may cancel each other out (balance). When an object rests on a surface: The weight of the object exerts a downward force on the surface The surface exerts an upwards force on the object The sizes of the two forces are the same

Forces ► Acceleration ► Unbalanced Forces
If the forces acting on an object do not cancel each other out… An unbalanced force will act on the object.

Forces ► Acceleration ► Scenarios
A stationary object will start to move in the direction of the unbalanced force An object moving in the direction of the force will speed up An object moving in the opposite direction to the force will slow down

Forces ► Acceleration ► Size of Resultant Force
VELOCITY VELOCITY VELOCITY The greater the force, the greater the acceleration.

Forces ► Acceleration ► Effect of Mass
The bigger the mass of an object… The greater the force needed to give the object a particular acceleration.

Forces ► Acceleration ► Newton
3 2 1 kg Speed (m/s) 1 1 2 3 Time (sec) One newton is the force needed to give a mass of one kilogram an acceleration of one metre per second squared. Force, mass and acceleration are related as shown: Force = Mass x Acceleration F m a 100 Newton 2 Kg 50 m/s2

Forces ► Acceleration ► Falling Objects
4 kg 2 kg 1 kg

Forces ► Acceleration ► Falling Objects II
Acceleration = Force (Weight) ÷ Mass x Gravity (10 N/kg) 40 N 20 N 10 N a = = = = 10 m/s2 4 kg 2 kg 1 kg Therefore, all objects fall at the same speed irrespective of mass (if we ignore air resistance, Friction)

Forces ► Acceleration ► Effect of Friction
Air Friction changes the situation Acceleration = Resultant Force (Weight – Friction) ÷ Mass Friction makes some of the weight effectively unavailable. 40 N 4 kg ≠ 20 N 2 kg 1 kg - 5 N

Forces ► Acceleration ► Changing Mass
kg Gravity N/kg Weight N Distance m Friction Resultant Acceleration m/s2 Time s 1 10 2 5 5.00 0.89 20 15 7.50 0.73 3 30 25 8.33 0.69 4 40 35 8.75 0.68 50 45 9.00 0.67 6 60 55 9.17 0.66 7 70 65 9.29 8 80 75 9.38 0.65 9 90 85 9.44 100 95 9.50

Forces ► Acceleration ► Mass vs Descent Time
Time (s) Mass (Kg)

Forces ► Acceleration ► Effect of Friction
If area changes, friction changes (eg Larger Parachute) Acceleration = Resultant Force (Weight – Friction) ÷ Mass Friction makes some of the weight effectively unavailable. 40 N 4 kg ≠ - 5 N - 10 N - 15 N

Forces ► Acceleration ► Changing Friction
Mass kg Gravity N/kg Weight N Distance m Friction Resultant Acceleration m/s2 Time s 70 10 700 2 100 600 8.57 0.68 150 550 7.86 0.71 200 500 7.14 0.75 250 450 6.43 0.79 300 400 5.71 0.84 350 5.00 0.89 4.29 0.97 3.57 1.06 2.86 1.18 2.14 1.37

Forces ► Acceleration ► Friction vs Descent Time
Time (s) Friction (N)

Forces ► Acceleration ► Time Formula
= velocity change ÷ time a v - u t 1. v u + at average speed distance 2. (u + v) ÷ 2 s 1. into 2. (u + u + at) ÷ 2 u is zero so… ½at ½at2 2s ÷ a t2 √(2s ÷ a) s = distance travelled u = initial velocity v = final velocity a = acceleration t = time taken

Forces ► Acceleration ► Equal and Opposite
Whenever two bodies interact… The forces they exert on each other are equal and opposite.

Forces ► Acceleration ► Unbalanced Forces
If the surface is not strong enough… we have a problem.

Forces ► Friction ► Ideas Map
2.3 Friction Fluids Solid Brakes Air Water Reaction Braking Friction = Weight Stopping Terminal Velocity

Forces ► Friction ► Types
air molecules A force of friction acts When an object moves through air or water When solid surfaces slide (or tend to slide) across each other.

Forces ► Friction ► Effects
The direction of this force of friction is always opposite to the direction in which the object or surface is moving. Friction causes objects to heat up and to wear away at their surfaces. The friction between solid surfaces is used in brakes which slow down and stop moving vehicles.

Forces ► Friction ► Braking
SPEED TIME The greater the speed of a vehicle: The greater the braking force needed to stop it in a certain distance The greater the distance needed to stop it with a certain braking force

Forces ► Friction ► Skidding
If too great a braking force is applied… Friction between a vehicle's tyres and the road surface may not be great enough to prevent skidding.

Forces ► Friction ► Stopping Time
long stopping distance short stopping distance reaction time braking time Speed Stopping time The overall stopping distance is greater if: The vehicle is initially travelling faster The driver's reactions are slower (due to tiredness, drugs, alcohol) There are adverse weather conditions (wet/icy roads, poor visibility) The vehicle is poorly maintained (e.g. worn brakes/tyres) The stopping distance of a vehicle depends on: The distance the vehicle travels during the driver's reaction time. The distance the vehicle travels under the braking force.

Forces ► Friction ► Terminal Velocity
60 m/s 4 m/s acceleration terminal velocity deceleration on ground weight friction force time The faster an object moves through a gas or a liquid (a fluid) the greater the force of friction which acts on it. When a body falls: Initially it accelerates due to the force of gravity Frictional forces increase until they balance the gravitational forces The resultant force eventually reaches zero and the body falls at its terminal velocity

Forces ► Friction ► Terminal Velocity II
Weight Friction = Weight therefore there is no acceleration

Forces ► Friction ► Driving
frictional forces driving force When a vehicle has a steady speed … The frictional forces balance the driving force.

Forces ► Momentum ► Ideas Map
2.5 Before Collision Mass After Collision x Before Objects have… Velocity After = Before Momentum After Before After

Forces ► Momentum ► Impact
Question: Would you rather be hit with a heavy or a light object? Answer: It depends on its speed.

Forces ► Momentum ► Elephant vs Cheetah
The greater the mass of an object… and the greater its speed in a particular direction (its velocity)… the more momentum the object has in that direction. Momentum has both magnitude (size) and direction.

Forces ► Momentum ► Calculation
Momentum, mass and velocity are related as shown: Momentum = Mass x Velocity 960 kg m/s 120 kg 8 m/s

Forces ► Momentum ► Collision
When an object collides with another.. The two objects exert a force on each other. These forces are equal in size but opposite in direction. Each object experiences a change in momentum which is equal in size but opposite in direction.

Forces ► Momentum ► Collision Calculation
2 Kg x 10 m/s 5 Kg x 6 m/s 2 Kg x 5 m/s 5 Kg x 8 m/s 50 Kg m/s 50 Kg m/s When a force acts on an object that is moving, or able to move… A change in momentum occurs. In any collision/explosion… the momentum after the collision/explosion is the same as… the momentum before the collision/explosion. (for a particular direction) Momentum is conserved when no other/external forces act on the colliding/exploding object(s).

Forces ► Momentum ► Collision Calculation II
The force, change in momentum and the time taken for the change are related as shown: Momentum Change (Impulse) = Force x Time 10 Kg m/s = 1,000 N x s

Forces ► Momentum ► Kinetic Energy
When objects collide, the total kinetic energy after the collision in a particular direction is normally less than before the collision. Elastic collisions are those involving no overall change in kinetic energy

Energy ► Work ► Ideas Map
5.4 Energy (J) Useful Energy Wasted Energy Power (J/s) Work (J) Calculated by Gravity Elastic Movement against force Inertia Friction

James Prescott Joule (1818 - 1889)
Energy ► Work ► Joule 1.0 J 0.8 J James Prescott Joule ( ) 0.6 J 1 metre 0.4 J 0.2 J 1 Newton 0.0 J Energy is measured in joules (J).

Energy ► Work ► Examples
10,000,000,000,000,000,000,000,000 J 100,000,000,000,000,000 J 100 J 1,000,000,000,000,000 J 10,000,000,000,000 J 100,000,000 J 1,000 J

Energy ► Work ► Effect of Force
When a force moves an object, energy is transferred. Energy transferred is also called work

Energy ► Work ► Calculation
Force Distance Energy = Force x Distance E F d 9,000 J 900 N 10 m

Energy ► Work ► Gravitational Potential Energy
Gravitational potential energy is the energy stored in an object Energy is stored because the object has been moved against the force of gravity. Work = Force x Distance Gravitational Potential Energy Weight Change in Height GPE W Δh 50 J 10 N 5 m

Energy ► Work ► Mass, Gravity and Weight
GRAVITY FIELD WEIGHT MASS Force on mass Amount of matter Region of influence Weight = Mass x Gravity W m g 10 N 1 kg 10 N/kg

Energy ► Work ► Elastic Potential Energy
Elastic potential energy is the energy stored in an elastic object. Energy is stored when work is done on the object to change its shape. Catapult designed by Leonardo da Vinci

Energy ► Work ► Kinetic Energy
Kinetic energy is the energy an object has because of its movement. An object has more kinetic energy: The greater its mass (and therefore inertia. The greater its speed Kinetic Energy = ½ Mass x Speed² KE ½ m v² 10 J 0.5 x 5 kg 4 (m/s)2

Energy ► Work ► Power 200,000,000 W 500,000 W Power (Watts) is a measure of how fast energy is transferred. The greater the power, the more energy is transferred in a given time Energy = Power x Time E P t 5,000,000 J 500,000 Watts 10 s

Energy ► Work ► Power and Human Activity
Power (W) 800 700 685 545 475 440 400 265 210 125 120 083 Activity playing basketball cycling (21 km/h) climbing stairs (116 steps/min) skating (15 km/h) swimming (1.6 km/h) playing tennis cycling (15 km/h) walking (5 km/h) sitting with attention focused standing at rest sitting at rest sleeping

Radioactivity ► Ideas Map
6 Atoms Decay Structure Radioactivity Types Properties Uses

Radioactivity ► Types ► Ideas Map
6.1 Alpha Types Beta Gamma Background Source Radioactivity Specific Speed of Decay Measuring Half Life Uses Sterilisation Tracer

Radioactivity ► Types ► Atoms
Every thing is made of atoms Iron on Copper The Kanji characters for "atom."

Radioactivity ► Types ► Stable vs Unstable
There are two kinds of atoms… Stable Unstable: Will emit radiation randomly once

Radioactivity ► Types ► Alpha Beta Gamma
Unstable atoms emit 3 types of radiation… 2 Protons ALPHA 2 Neutrons BETA High Energy Electron GAMMA ALUMINIUM High Frequency Wave PAPER LEAD

Radioactivity ► Types ► Sources
loft insulation carpets There are radioactive substances all around us, including in the ground, in the air, in building materials and in food. Radiation also reaches us from space. The radiation from all these sources is called background radiation.

Radioactivity ► Types ► Ions
-1 + 1 +1 + 1 +1 -1 -1 Normal Atom Ion When radiation from radioactive materials collides with neutral atoms or molecules these may become charged (ionised). When radiation ionises molecules in living cells it can cause damage, including cancer. The larger the dose of radiation the greater the risk of cancer.

Radioactivity ► Types ► Ionising Radiation
Higher doses of ionising radiation can kill cells. they are used to kill cancer cells and harmful microorganisms.

Radioactivity ► Types ► Measuring Thickness
As radiation passes through a material it can be absorbed. The greater the thickness of a material the greater the absorption. The absorption of radiation can be used to monitor/control the thickness of materials.

Radioactivity ► Types ► Interaction with Body
least dangerous ALPHA BETA most dangerous GAMMA most dangerous least dangerous Used as tracer

Radioactivity ► Types ► Monitoring Dosage
Low Dosage High Dosage Workers who are at risk from radiation often wear a radiation badge to monitor the amount of radiation they have been exposed to over a period of time. The badge is a small packet containing photographic film. The more radiation a worker has been exposed to, the darker the film is when it has been developed.

Radioactivity ► Types ► Half Life
100 Undecayed Atoms 50 14 28 Time (s) The half-life of a radioactive substance: Is the time it takes for the number of parent atoms in a sample to halve. Is the time it takes for the count rate from the original substance to fall to half its initial level.

Radioactivity ► Structure ► Ideas Map
6.2 Atomic Structure Discovery Nucleus Nucleons Scattering Exp. Proton Neutron Electron Type of atom Isotope Fission Element Dating

Radioactivity ► Structure ► Relative Size
Neutron Proton Electron Atoms have a small central nucleus made up of protons and neutrons around which there are electrons. To scale above nucleus would be size of a grain of sand.

Radioactivity ► Structure ► Rutherford Expectation
The ‘plum pudding’ model of matter said that atoms were solid and uniformly positive with specks of negativity. If this was the case even a small thickness of material should block a stream of alpha particles. Ernest Rutherford decided to test this idea Lord Ernest Rutherford ( ) What they expected…. alpha particle source alpha detectors gold leaf

Radioactivity ► Structure ► Rutherford Result
What actually happened…. straight through deflection reflected back Conclusion 1 : The plum pudding model must be wrong

Radioactivity ► Structure ► Rutherford Conclusion
Conclusion 2 : Nuclei are positive and far apart + + + + + + + simplified gold nucleus

Radioactivity ► Structure ► Masses
Proton Neutron Electron Kilograms are inconvenient for such tiny masses… So the Atom Mass Unit was invented. Protons and neutrons weigh 1 AMU by definition, an electron is 1/2000 AMU

Radioactivity ► Structure ► Notation
Ne + = = The number of electrons is equal to the number of protons in the nucleus therefore… The atom as a whole has no electrical charge. = 0 The total number of protons and neutrons (nucleons) in an atom is called its mass (nucleon) number.

Radioactivity ► Structure ► Proton Number
3 protons therefore Lithium All atoms of a particular element have the same number of protons.

Radioactivity ► Structure ► Elements
1 proton therefore Hydrogen 2 protons therefore Helium 3 protons therefore Lithium 4 protons therefore Berylium Atoms of different elements have different numbers of protons.

Radioactivity ► Structure ► Isotopes
normal Hydrogen 1 extra neutron 2 extra neutrons 3 extra neutrons isotopes of hydrogen Atoms of the same element which have different numbers of neutrons are called isotopes.

Radioactivity ► Structure ► Beta Decay
Radioactive isotopes (radioisotopes or radionuclides) are atoms with unstable nuclei. When an unstable nucleus splits up (disintegrates): It emits radiation. A different atom, with a different number of protons, is formed. For each electron emitted, a neutron in the nucleus becomes a proton.

Radioactivity ► Structure ► Fission
Nuclear reactors use a process called nuclear fission. When an atom with a very large nucleus is bombarded with neutrons: The nucleus splits into two smaller nuclei. Further neutrons are released which may cause further nuclear fission resulting in a chain reaction. The new atoms which are formed are themselves radioactive.

Radioactivity ► Structure ► Comparative Energies
= 3,500,000 g of Coal 1 g of Uranium The energy released by an atom during radioactive disintegration or nuclear fission is very large compared to the energy released when a chemical bond is made between two atoms.

Radioactivity ► Structure ► Carbon Dating
The tomb of Rameses IX lies in the centre of the Valley of the Kings Wooden Bowl dated to 1000 BC The older a particular radioactive material, the less radiation it emits. This idea can be used to date materials, including rocks.

Radioactivity ► Structure ► Carbon Dating
100% 74% 5,000yr 10,000yr 1,000yr The half life of Carbon 14 is 5,730 years. During one half-life, half of the radioactive atoms initially present in a sample decay. This idea can be used to date materials.

Radioactivity ► Structure ► Non-Carbon Dating
58% 42% 15,000 yr Uranium isotopes, which have a very long half-life, decay via a series of relatively short-lived radioisotopes to produce stable isotopes of lead. The relative proportions of uranium and lead isotopes in a sample of igneous rock can, therefore, be used to date the rock The proportions of the radioisotope potassium-40 and its stable decay product argon can also be used to date igneous rocks from which the gaseous argon has been unable to escape.

End of main section

► Key Terms ELECTRICITY FORCE WAVES SPACE ENERGY RADIOACTIVITY
Alternating current Ammeter Ampere Anode Battery Capacitor Cathode Cell Charge Circuit breaker Conductor Core Coulomb Current Diode Direct current Dynamo Earthing Electrical energy Electrical charge Electric current Electrode Electrolysis Electrolyte Electromagnet Electromagnetic induction Electron Electrostatic forces Free electron Friction Fuse Generator Hertz Input sensor Insulation Insulator Ion Ionise Joule Kilowatt Kilowatt hour Light-dependent resistor Logic gate Magnet Magnetic field Motor effect Ohm Output device Parallel/series circuits Potential difference Potential divider Power Primary coil Processor Relay Resistance FORCE Acceleration Air resistance Braking distance Centre of mass Centripetal force Decelerate Drag Elastic collision Friction Gravity Kinetic energy Mass Moment Momentum Newton Pivot Speed Terminal velocity Thinking distance Velocity Weight WAVES Amplitude Analogue signal Compression Converging lens Core Crests Critical engle Crust Cycle Diffraction Digital signals Diverging lens Electromagnetic spectrum Electromagnetic waves Fetal imaging Fetus Focus Frequency Hertz Lithosphere Longitudinal wave Magma Mantle Normal P waves Rarefraction Real image Refraction Seismic waves Seismograph S waves Subduction zone Tectonic plates Total internal reflection Transverse waves Troughs Ultrasound Vibration Virtual image Wavelength Waves Wave speed SPACE Artificial satellite Big bang Black hole Comet Fusion Galaxy Geostationary satellite Gravity Light year Milky way Moon Orbit Planet Red planet Red giant Red shift Satellite Solar system Star Sun Universe White dwarf ENERGY Conduction Convection Efficiency Elastic potential energy Electrical energy Fossil fuels Free electrons Generator Geothermal energy Global warming Gravitational potential energy Greenhouse effect Hydroelectric Kinetic energy Non-renewable resources Power Radiation Renewable energy Turbine Work RADIOACTIVITY Activity Alpha Atom Atomic number Background radiation Beta Chain reaction Cosmic ray Count rate Decay Electrons Electromagnetic spectrum Element Gamma Gieger-Muller tube Half-life Ionise Isotope Mass number Neutron Nuclear fission Nucleon Nucleus Proton Radiation Radioactive dating Radioactive decay Radioactive emissions Radioactive tracer Radioactivity Radioisotopes Random Resistor Secondary coil Solenoid Thermistor Transformer Transistor Volt Voltage Voltmeter Watt

Electromagnetic spectrum Total internal reflection
► Connections Output device Radioisotopes Light-dependent resistor Watt Joule Transistor Logic gate Processor Gravity Terminal velocity Element Mass number Power Thermistor Velocity Isotope Kilowatt hour Input sensor Weight Potential divider Energy Decelerate Atomic number Ohm Direction Neutron Kilowatt Speed Drag Proton Relay Air resistance Potential difference Resistor Insulator Graphs Nucleon Braking distance Voltage Hertz Cost Acceleration Background radiation Volt Insulation Control Nucleus Resistance Friction Stopping Distance Thinking distance Chain reaction Electrons Forces Voltmeter Mains Nuclear fission Emissions Decay Atom Charge Moments Voltage Momentum Centre of mass Circular Structure Random Dating Mass Gieger-Muller tube Newton Tracer Circuits Pivot Alpha Uses Centripetal force Count rate Beta Cycle Types Radioactivity Electricity Hertz Elastic collision Kinetic energy Half-life Cosmic ray Gamma Troughs Crests Electromagnetic spectrum Secondary coil Wave speed Frequency Amplitude Primary coil Generator Wavelength Normal Magnet Diffraction Turbine Electrical energy PHYSICS Longitudinal Magnetic field Transformer Characteristics Refraction Critical angle Induction Motor effect Solenoid Transverse Total internal reflection Energy Electromagnetism Space Converging lens Virtual image Optical Focus Global warming Waves Real image Fossil fuels Big bang Diverging lens Ultrasound Thermal Solar Fetal imaging Greenhouse effect Resources Comet Sound Non-renewable Conduction Solar system Rarefraction Convection Geothermal Universe Vibration Renewable Efficiency Radiation Tectonic Sun Seismic Compression Magma Hydroelectric Black hole Red shift Crust Gravitational potential energy Galaxy Planets Orbit Core Lithosphere Work Mantle Kinetic energy Milky way Electromagnetic Spectrum Star Satellite Subduction zone Power Light year Moon Artificial satellite Seismograph Elastic potential energy Red giant Fusion Geostationary Polar Digital signals S waves P waves White dwarf Analogue signal

ELECTRICITY ► phenomena explained by electrons
ATOM small unit of matter ELECTRON part of atom, can leave PROTON part of atom, cannot leave PROPERTIES what features or attributes does an electron have MEASUREMENT what units are used to count electrons EFFECTS things that happen because of electrons ABILITY TO MAKE THINGS MOVE charge, there are two types. negative and positive WORDS FOR LARGE NUMBERS are convenient eg the word ‘year’ instead of 31,536,000 seconds MOVING ELECTRONS current, flow of charge, electricity STATIONARY ELECTRONS very large numbers of electrons grouped together. static electricity, ’static’, electrostatics ELECTRONS HAVE A NEGATIVE CHARGE sometimes electrons are referred to as ‘charge’. The charge on proton is positive EXTRA ELECTRONS negatively charged NORMAL NUMBER OF ELECTRONS no charge, neutral LACK OF ELECTRONS positively charged COULOMB a word for a large number of electrons - REPELLED move away from other electrons ATTRACTED move towards protons - + - + + - + - Electrons move round circuits A circuit is a number of components eg bulbs connected by wires 3. A battery provides a stream of electrons 1. Charged objects attract neutral ones 2. Positive and negative objects attract 3. Like charged objects repel MEASUREMENT how many electrons passing a point ENERGY electrons can deliver energy TYPES OF MOVEMENT EASE OF MOVEMENT BACKWARDS AND FORWARDS alternating current ALWAYS ONE WAY direct current EASY conductor eg copper DIFFICULT SOMETIMES DIFFICULT IMPOSSIBLE insulator eg plastic ELECTRONS PER SECOND measured in amps ENERGY PER ELECTRON measured in volts MAINS delivers energy to the home BATTERY WHEN DARK light dependent resistor ENERGY DELIVERED PER SECOND measured in watts, joules per second Environment Dependent ENERGY COSTS MONEY EXCESSIVE ENERGY IS DANGEROUS WHEN COLD thermistor DIFFICULTY SET BY USER variable resistor IF 1000 JOULES of energy is delivered per second… SAFETY MEASURES WIRE IS LONG INDIRECT CONTROL DELIBERATE WEAK POINT AUTOMATIC OFF SWITCH …for 1 HOUR WIRE IS THIN RELAY a small safe current switches on a big unsafe current FUSE when the current surges a thin section of wire melts CIRCUIT BREAKER very quick off switch ..the electricity company call it a UNIT or kilowatthour…a unit costs about £0.08 POOR CONDUCTOR fixed resistor

FORCE AND MOTION ► a push or a pull which creates movement
OBJECTS HAVE... VELOCITY CONSTANT VELOCITY eg 0 m/s or 100 m/s BALANCED FORCES FORCES ACTING ON THEM CHANGING VELOCITY UNBALANCED FORCES SPEED m/s DIRECTION GRAPHS representing motion CHANGING SPEED CHANGING DIRECTION EXAMPLES CHARACTERISTICS how can we describe a force TIME seconds DISTANCE metres CONTACT FORCES muscular, friction NON►CONTACT FORCES field forces. gravity, magnetism INCREASE acceleration DECREASE deceleration TEMPORARY FORCE direction changes CONSTANT FORCE direction always changes CONSTANT SPEED D T S Mass Circular eg ball swung round on a string moon orbiting earth SIZE measured in newtons DIRECTION CHANGING SPEED Momentum D S weight friction Friction = Weight Acceleration = 0 Speed = 60 m/s Terminal Velocity T T sober, well rested, good brakes, dry road drunk, tired, bad brakes, icy road stop braking

WAVES ► movement of energy but not matter
TYPES OF MOVEMENT SIDE TO SIDE UP AND DOWN A to B OSCILLATION also known as vibration KNOCK-ON EFFECTS original movement causes movement elsewhere ISOLATED original movement only WAVES CHARACTERISTICS how do we describe waves BEHAVIOUR what do waves do TYPES How big is the oscillation? The AMPLITUDE is 2 metres OSCILLATION IN DIRECTION OF TRAVEL longitundinal waves OSCILLATION AT 90O TO DIRECTION OF TRAVEL transverse waves CHANGE SPEED eg moving from air to glass SPREAD OUT when passing thru a gap: diffraction CHANGE DIRECTION How long is the wave from peak to peak? The WAVELENGTH is 5 metres How often does a wave pass? The FREQUENCY is 2 waves per second or 2 hertz BOUNCING OFF reflection BENDING light refracts when it hits glass at an angle Sound SLINKY EARTHQUAKES ROPE SEA WAVES ELECTROMAGNETIC 300,000 km/s How fast is the wave travelling? The SPEED of the wave is 10 metres per second SINGLE WAVE MANY PARALLEL WAVES GAMMA X RAY ULTRAVIOLET LIGHT INFRARED MICROWAVE RADIO AMPLITUDE CAN CARRY INFORMATION analogue or digital BENT TOWARDS each other by a convex lens BENT AWAY FROM each other by a concave lens WAVELENGTH distorted wave still readable as 1 or 0 digital is better because the message is preserved even if the wave is distorted

SPACE ► universe, galaxy, solar system, star, planet, satellite
everything we can see HISTORY STRUCTURE LIFE Evidence for PAST PRESENT FUTURE DIRECT INDIRECT MASSIVE EXPLOSION Big Bang EXPANDING CONTRACTION? Big Crunch? OUR GALAXY 100 billion stars called the milky way OTHER GALAXIES 100 billion Finding live or fossilised organisms Broadcast signals Chemical changes in atmosphere Eg O2 EVIDENCE FOR EXPANSION RED SHIFT light from distance stars has a longer wavelength than we would ‘expect’ if universe were static STARS massive nuclear furnaces OUR STAR, THE SUN is orbited by.. ENERGY SOURCE LIFE CYCLE NUCLEAR FUSION hydrogen and helium fusing together to create.. THE EARTH is orbited by.. 8 OTHER PLANETS PAST gravity pulls dust together. fusion begins PRESENT expansive nuclear forces = gravity FUTURE Mercury, Venus, (Earth), Mars, Jupiter, Saturn, Uranus, Neptune, Pluto HEAT AND LIGHT HEAVIER ATOMS which make life possible eg carbon SATELLITES objects held in circular path by earth’s gravity MEDIUM STAR BIG STAR VERY BIG STAR NATURAL ARTIFICAIL expansive forces win over gravity MOON causes tides USES TYPES OF ORBIT STAR SWELLS into a red giant STAR EXPLODES supernova BLACK HOLE ultra dense, no light escapes MONITOR EARTH weather, military MONITOR SPACE eg hubble space telescope COMMUNICATIONS APPARENTLY FIXED IN THE SKY geostationary orbit MOVES IN THE SKY polar orbit

ENERGY ► the ability to make things happen
TYPES CHARACTERISTICS POTENTIAL ENERGY stored energy KINETIC ENERGY movement energy LARGE SCALE can see SMALL SCALE can’t see LARGE SCALE can see SMALL SCALE can’t see MEASURED in joules CANNOT BE DESTROYED MATERIAL UNDER TENSION strain HEIGHT gravitational potential energy BONDS BETWEEN ATOMS chemical UNSTABLE ATOMS nuclear MOVING CAR ROTATION of magnet CURRENT CREATES MOVEMENT motor ELECTRONS FLOWING magnetic field created ATOMS VIBRATING heat or thermal energy CANNOT BE CREATED MOVEMENT CREATES CURRENT generator ENERGY CAN CHANGE TYPE rate of change is measured in watts eg bow and arrow, spring eg water behind dam, sky diver eg coal, gas, oil, wood eg uranium VIBRATIONS CAN SPREAD IN 3 WAYS F D F D F D STORED ENERGY eg petrol is changed into… 1. ATOMS COLLIDE WITH THEIR NEIGHBOURS conduction 2. ATOMS MOVE TO A NEW LOCATION convection 3. WAVE TRANSMISSION radiation ENERGY USEFUL TO HUMANS known as work eg a moving car ENERGY NOT USEFUL TO HUMANS known as dissipated energy eg heat from car engine eg saucepan base eg boiling water eg warmth from sun GREATER FORCE means greater energy maximising the useful energy makes the car EFFICIENT GREATER DISTANCE means greater energy N S MAGNET MOVING WIRE MOVING Creating current without contact (Induction)

RADIOACTIVITY ► fast moving particles and high energy waves
ATOM small unit of matter STRUCTURE what is an atom made of STABILITY OF ATOM STABLE ATOMS stay the same forever UNSTABLE ATOMS break apart, pop, decay RANDOMLY by kicking out (emitting) particles and energy CENTRAL CORE nucleus OUTER CLOUD . NUCLEON very small unit of matter HOW UNSTABLE IS THE ATOM? how long does it take for… FORMATION WHAT ATOMS EMIT BLOCKED BY (absorbed by) ALL ATOMS TO DECAY HALF THE ATOMS TO DECAY NATURAL UNNATURAL 2 PROTONS & 2 NEUTRONS EMITTED alpha radiation card lead . aluminium PROTON positively charged (exerts a force) NEUTRON not charged (exerts no force) ELECTRON smallest unit of matter negatively charged (exerts a force) DIFFICULT TO PREDICT EASY TO PREDICT bombarded with neutrons . 1 ELECTRON EMITTED beta radiation CONTROLLED nuclear reactor RAPID nuclear bomb VERY UNSTABLE short half►life VERY STABLE long half►life HIGH ENERGY WAVE EMITTED gamma radiation DESCRIPTION AND NOTATION 50% 1ms 50% 1mil. yr. TYPES OF ATOM elements normal atom HYDROGEN ATOMS always have one proton alpha beta gamma INSIDE BODY skin cell: dead tissue cell: live damaged cell OUTSIDE BODY MEDICAL USE isotopes have extra neutrons HELIUM ATOMS always have two protons 98% 1% protons in atoms alpha particles like charges repel Rutherford used alpha particle to show that nuclei are far apart a LITHIUM ATOM always has three protons mass number 7 Li proton number 3 chemical symbol

► Links ½ m Frequency (f) Wavelength (λ) Acceleration (a) Time (t)
Mass (m) Velocity (v) Gravitational Field Strength (g) Momentum Current (I) Resistance (R) Force (F) v2 Charge (Q) ½ m Weight (w) Distance (d) Voltage (V) Impulse Change in Height (Δh) Moment Power (P) GPE KINETIC WORK ELECTRICAL ELECTRICAL Energy (E) Efficiency Unit Cost Useful Energy Total Cost

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