P1 - Universal physics 19 September 2018 A Massawe.

P1 - Universal physics 19 September 2018 A Massawe

How science works this is the quantity that you change
this is what you measure this is what must be kept the same to ensure a fair test an idea based on observations without experimental evidence data collected by someone else, you may find it in a book or on the internet Independent variable – Dependent variable - Control variable – Hypothesis – Secondary evidence - 19 September 2018 A Massawe

How do scientist validate results?
1. they repeat experiment results 2. they publish their findings in scientific journals 3. conference presentation 4. peer review/other scientists investigate the same findings. 19 September 2018 A Massawe

Models of the solar system
Geocentric model(Ptolemy) - the earth at the centre and all the planets and the sun orbiting around it Heliocentric model(Nicolaus Copernicus) - the sun at the centre of the universe, based on observations with the telescope 19 September 2018 A Massawe

Observing the universe
observe visible light from space The Hubble telescope is an optical telescope in space Optical telescopes on the ground have some disadvantages: 1. 2. Optical telescopes they can only be used at night they cannot be used if the weather is poor or cloudy. 19 September 2018 A Massawe

Many objects in space do not give out visible light but give out other types of energy-carrying waves like and The Planck space telescope detects radio waves microwaves microwaves 19 September 2018 A Massawe

detect radio waves coming from space, they are usually very large and expensive. Advantage over optical telescopes – 1. 2. Radio telescopes can be used in bad weather because the radio waves are not blocked by clouds as they pass through the atmosphere. can also be used in the daytime as well as at night. 19 September 2018 A Massawe

Telescopes mirrors lenses
Telescopes use and to bend, magnify and focus the light. Parallel light rays entering a convex lens come out and pass through at a point known as the Converging lenses are used in a mirrors lenses focal point refracting telescope 19 September 2018 A Massawe

Investigating converging lenses
A Converging lens can be used to produce a magnified image. The amount of magnification depends on: 1. 2. Two types of image can be seen. 1. A Is the image formed where the light rays are focused. 2. A is one from which the light rays appear to come, but don’t actually come from that image like in a plane (flat) mirror. How curved the surface of the lens is How far the object is from the lens real image virtual image 19 September 2018 A Massawe

Object more than two focal lengths from the lens image is inverted, smaller, appear between 1 and 2 focal lengths, real image 19 September 2018 A Massawe

Two focal lengths in front image is inverted, same size, appears at 2 focal lengths, real image 19 September 2018 A Massawe

Between one and two focal lengths image is inverted, made bigger, appear beyond 2 focal lengths, real image 19 September 2018 A Massawe

One focal length no image is formed 19 September 2018 A Massawe

Object is less than one focal length from the lens. image right way up, image made bigger, virtual image 19 September 2018 A Massawe

Refracting telescopes
A refracting telescope works by bending light through a lens so that it forms an image Problems with refracting telescopes: 1. 2. some of the light reflects off the lens so the image is very faint the size of the lens is limited 19 September 2018 A Massawe

Reflecting telescopes
In a reflecting telescope the image is formed by reflection from a It is then magnified by a curved mirror Convex lens (the eyepiece) 19 September 2018 A Massawe

Compare and contrast lenses and mirrors
1. A convex lens acts a lot like a concave mirror. Both converge parallel rays to a focal point, and form images with similar characteristics. 2. A concave lens acts a lot like a convex mirror. Both diverge parallel rays away from a focal point, and form only virtual, smaller images. Similarities 19 September 2018 A Massawe

Compare and contrast lenses and mirrors
1. Light reflects from a mirror. Light goes through, and is refracted by, a lens (with some light being reflected off the lens). 2. Lenses have two focal points, one on either side of the lens. 3. A concave mirror converges parallel light rays to a focal point. For lenses, parallel rays converge to a point for a convex lens. A convex mirror diverges light, as does a concave lens. Differences 19 September 2018 A Massawe

Refraction in different materials
Remember the word: TAGAGA Towards (normal) Air Glass Away (from normal) 19 September 2018 A Massawe

Effects of refraction 19 September 2018 A Massawe

What are waves? Waves are from place to place without matter (solid, liquid or gas) being transferred, e.g. Mexican wave in a football crowd vibrations that transfer energy Waves travel through medium No medium required sound waves seismic waves visible light infrared rays microwaves other types of electromagnetic radiation 19 September 2018 A Massawe

Transverse or longitudinal waves?
Transverse waves Longitudinal waves the vibrations are along the parallel to the direction of travel e.g. - sound, - P waves (a type of seismic wave) the vibrations are at right angles to the direction of travel e.g. - light, - electromagnetic radiation, - water waves, - S waves (a type of seismic wave) 19 September 2018 A Massawe

What are waves? wavelength
The is the distance between a point on one wave and the same point on the next wave The is the maximum distance of the particles in a wave from their normal positions The of a wave is the number of waves produced by a source each second. amplitude frequency 19 September 2018 A Massawe

How fast do waves travel?
wave speed (m/s) = frequency (Hz) × wavelength (m) wave speed frequency wavelength 19 September 2018 A Massawe

Reflection Sound waves and light waves from surfaces. The angle of incidence equals the Smooth surfaces produce strong when sound waves hit them Rough surfaces sound and light in all directions reflect angle of reflection echoes scatter 19 September 2018 A Massawe

Refraction change speed
Sound waves and light waves when they pass across the boundary between two substances with different densities, e.g. air and glass. This causes them to change direction and this effect is called There is no change in direction if the waves cross the boundary at an angle of in that case they carry straight on (although there is still a change in speed). change speed refraction 90° 19 September 2018 A Massawe

Electromagnetic spectrum
Wavelength () increases Frequency (f) increases Gamma X-ray Ultra-violet Light Infra-red Microwaves Radio Gate X Usually Lets In Most Radiation Can you think of a phrase that would help you remember this order? High frequency Short wavelength High energy Most penetrating Low frequency Long wavelength Low energy Least penetrating Low frequency Long wavelength Low energy Least penetrating High frequency Short wavelength High energy Most penetrating 19 September 2018 A Massawe

Hazards of electromagnetic radiation
Microwaves cause internal heating of body tissues Infrared radiation is felt as heat and causes skin burns damage cells, causing mutations (which may lead to cancer) and cell death X rays Gamma rays also damage cells, causing mutations (which may lead to cancer) and cell death. 19 September 2018 A Massawe

The three main types of ultraviolet radiation, and some of their effects
frequency hazard UV C high causes severe damage to cells, skin cancer UV B medium causes severe sunburn and damage to cells UV A low weaker effects than UV B 19 September 2018 A Massawe

Uses of electromagnetic radiation
Radiowaves – broadcasting, communications & satellite transmissions – cooking, communications & satellite transmissions - cooking, thermal imaging, short range communications, optical fibres, TV remote controls & security systems – vision, photography & illumination Microwaves Infrared Visible light 19 September 2018 A Massawe

Uses of electromagnetic radiation
– security marking, fluorescent lamps, detecting forged bank notes & disinfecting water - observing the internal structure of objects, airport security scanners & medical X-rays - sterilising food and medical equipments, detection of cancer and its treatment Ultraviolet X-rays Gamma 19 September 2018 A Massawe

Exam tip To make your answer as full as possible you should include:
1. the advantages and disadvantages of each type of radiation 2. clearly indicate the precise use and why 3. include information about frequency and wavelength 19 September 2018 A Massawe

Ionising radiation Alpha, beta and gamma are ionising radiation: they can knock electrons out of atoms and form charged particles Radiation can be harmful, but it can also be useful - the uses of radiation include to: 1. detect smoke 2. gauge the thickness of paper 3. treat cancer 4. sterilise medical equipment. 19 September 2018 A Massawe

Types of radiation alpha beta gamma
Nuclear radiation comes from the nucleus of an atom of substances which are All radiation transfers energy. There are three types of nuclear radiation: radioactive alpha, beta and gamma alpha beta gamma 19 September 2018 A Massawe

The solar system The solar system consists of: 1. a star - the Sun
2. satellites - moons - in orbit around most of the planets 3. comets and asteroids in orbit around the Sun. 4. eight planets, including the Earth, and smaller dwarf planets, such as Pluto, Ceres and Eris. 19 September 2018 A Massawe

Space exploration The Search for Extra-Terrestrial Intelligence (SETI) is a programme that uses to look for non-natural signals coming from space radio telescopes photograph planets looking for evidence of life touch down on planets and take a soil sample, which is analysed for evidence of life. Space probes Space landers 19 September 2018 A Massawe

What is a spectrometer? Spectrometer is an instrument that can split up light to show the colours of the spectrum 19 September 2018 A Massawe

The origins of the Universe
Scientists believe that the universe began in a hot 'big bang' about 13 billion years ago Two evidences of the Big Bang Theory are; 1. the existence of a microwave background radiation, 2. red-shift. 19 September 2018 A Massawe

Other theories for the origin of the universe
The suggests that this universe is one of many - some that have existed in the past, and others that will exist in the future When the universe contracts in a Big Crunch, a new universe is created in a new Big Bang. The suggests that as the universe expands new matter is created, so that the overall appearance of the universe never changes. Oscillating Theory Steady State Theory 19 September 2018 A Massawe

Life cycle of a star 19 September 2018 A Massawe

The future of other stars
The life of stars depend on their A heavy-weight star will still become a red giant, but then: 1. it blows apart in a huge explosion called a supernova 2. the central part left behind forms a neutron star, or even a black hole, if it is heavy enough 3. black holes have a large mass, and a large gravity - even light cannot escape them because their gravitational field is so strong masses A supernova is an exploding star 19 September 2018 A Massawe

Evidence for the Big Bang Theory
Red-shift - red is a longer wavelength of light, this means that the galaxies must all be moving away from us Cosmic Microwave Background radiation - electromagnetic radiation which was present shortly after the big bang is now observed as background microwave radiation. A satellite called COBE mapped the background microwave radiation of the universe 19 September 2018 A Massawe

Evidence for the Big Bang Theory
Interpretation The light from other galaxies is red-shifted. The further away the galaxy, the more its light is red-shifted. Cosmic Microwave Background (CMB) The other galaxies are moving away from us. This evidence can be used to explain both the Big Bang theory and Steady State universe. The most likely explanation is that the whole universe is expanding. This supports the theory that the start of the universe could have been from a single explosion. The relatively uniform background radiation is the remains of energy created just after the Big Bang. 19 September 2018 A Massawe

Doppler effect for a moving sound source
Long wavelength Low frequency Short wavelength High frequency 19 September 2018 A Massawe

Ultrasound and infrasound
Sound waves are waves that must pass through a medium have a frequency above the normal range of human hearing - they can be used to has a frequency below normal hearing - can be used to longitudinal Ultrasound waves scan for birth defects in unborn babies scan for defects in manufactured equipment. Infrasound track animals monitor seismic activity 19 September 2018 A Massawe

Sound waves When an object vibrates, it produces sound. The bigger the vibrations, the greater the amplitude and the louder the sound 1 and 2 - two sounds with the same frequency but different amplitude. Sound 1 (smaller amplitude) is quieter than sound 2. 2 and 3 - two sounds with the same amplitude but different frequencies. The faster the vibrations, the higher the frequency and the more highly pitched the sound. So sounds 2 and 3 have the same volume (loudness), but 3 (higher frequency) is higher pitched. 19 September 2018 A Massawe

Ultrasound When ultrasound waves reach a boundary between two substances with different densities, they are partly reflected back and detected e.g. sound travels through water at about 1,400 m/s. If it takes 0.5 s for a sound to reach a boundary and reflect back to the detector, the total distance travelled is: distance = speed × time = 1,400 × 0.50 = 700m 19 September 2018 A Massawe

Sonar Sonar is used on ships and submarines to detect fish or the sea bed. A pulse of ultrasound is sent out from the ship. It bounces off the seabed or shoal of fish and the echo is detected. The time taken for the wave to travel indicates the depth of the seabed or shoal of fish 19 September 2018 A Massawe

Infrasound Infrasound has frequency less than 20Hz, this is below the range that humans can hear (20-20,000Hz). Infrasound is detected using a microphone. Three uses of infrasound: 1. to detect volcanic eruptions - as a volcano erupts it produces infrasound, which can be detected even if the volcano is in a remote location far away 2. to track the passage of meteors through the atmosphere 3. to track animals (elephats use infrasound to communicate) even if they are hidden in dense forests. This helps with the conservation and protection of these animals. 19 September 2018 A Massawe

Seismic waves The crust and upper mantle are broken into large pieces called These plates move slowly, but can cause and where they meet. The seismic waves produced by an earthquake are monitored and tracked. tectonic plates earthquakes volcanes - liquid nickel and iron - Solid nickel and iron 19 September 2018 A Massawe

Seismic waves Earthquakes happen when large parts of the Earth's crust and upper mantle move suddenly Earthquakes produce shockwaves called seismic waves. These waves can be detected using seismographs. P waves S waves type of wave longitudinal transverse relative speed faster slower can travel through solids and liquids solids only 19 September 2018 A Massawe

Difference between S and P waves
S-waves - transverse - slow moving - travel through solids only P-waves - longitudinal - fast moving - travel through liquids and solids only 19 September 2018 A Massawe

Producing electricity
An electric current can be produced by moving a magnet inside a coil of wire attached to a sensitive ammeter, the needle is seen to move. This means the magnet causes the to move around the circuit as a free electrons current 19 September 2018 A Massawe

Here the magnet is being pushed into the coil. The ammeter shows current induced in a positive direction. Now the magnet is stationary inside the coil. There is no current being produced in the coil, shown by the zero reading on the ammeter The magnet is being pulled out The ammeter shows current being induced in the opposite direction to before. 19 September 2018 A Massawe

The size of this induced current can be increased by 1. move the magnet faster 2. use a stronger magnet 3. increase the number of turns on the coil 4. increase the area of the coil. 19 September 2018 A Massawe

Direct and alternative current
Direct current – DC, current flows in only one direction . Batteries and solar cells supply DC electricity. The diagram shows an oscilloscope screen displaying the signal from a DC supply. Alternating current – AC, current constantly changes direction. Mains electricity is an AC supply. The UK mains supply is about 230V. It has a frequency of 50Hz, which means that it changes direction and back again 50 times a second. 19 September 2018 A Massawe

Generators (bicycle dynamo) induce a current by spinning a magnet inside a coil of wire When this happens, a potential difference - voltage - is produced between the ends of the coil, which causes a current to flow. As the bicycle moves, the wheel turns a magnet inside a coil This induces enough electricity to run the bicycle's lights The faster the bicycle moves, the greater the induced current and the brighter the lights. 19 September 2018 A Massawe

Large-scale electricity production
Turning generators indirectly - generators can be turned indirectly using fossil or nuclear fuels 1. Heat is released from fuel and boils the water to make steam. 2. The steam turns the turbine. 3. The turbine turns a generator and electricity is produced. 4. The electricity goes to the transformers to produce the correct voltage 19 September 2018 A Massawe

Different sources of energy
Renewable energy resources include: wind energy tidal waves hydroelectric power geothermal energy solar energy biomass energy, for example energy released from wood 19 September 2018 A Massawe

Solar cells or Solar energy
Solar cells (or photocells) turn light energy from the Sun directly into direct current electricity. Advantages Disadvantages Its renewable No maintenance No power lines required No fuel Long lifetime No green house gases Expensive to build Low efficiency – requires large area Manufacture causes pollution Low power output 19 September 2018 A Massawe

Hydroelectricity A dam is built to trap water, usually in a valley where there is an existing lake. Water is allowed to flow through tunnels in the dam, to turn turbines and thus drive generators. Advantages Disadvantages No waste or pollution Very reliable Low running cost Quick start-up time Electricity can be generated constantly Requires hilly areas Destroys habitats Expensive to build 19 September 2018 A Massawe

Wind turbines Wind turbines (or aero-generators) use large blades to capture the kinetic energy of the wind. This kinetic energy is used to directly turn a turbine and produce electricity. Advantages Disadvantages No waste or greenhouse gases No fuel is needed Can be tourist attractions Noisy May spoil views Kill birds The amount of electricity generated depends on the strength of the wind. 19 September 2018 A Massawe

Geothermal energy Hot rocks underground heat water to produce steam.
Holes are drilled down to the hot region, steam comes up to drive turbines, which drive electric generators Advantages Disadvantages No pollution No fuel is needed Easy and cheap to run Hot rocks are not available everywhere Geothermal site can run out of steam Hazardous gases or minerals may come up 19 September 2018 A Massawe

Tidal power These work rather like a hydro-electric scheme, except that the dam is much bigger. Advantages Disadvantages High power output Reliable power source Long lifetime Low running costs No fuel needed Tides are predictable Not expensive to maintain Tidal range varies Destroys habitats Expensive to build 19 September 2018 A Massawe

Biomass Wood is burnt to heat our homes and cook our food.
Sugar cane can be fermented to make alcohol, which can be burned to generate power. Advantages Disadvantages The fuel is cheap Less demand on the fossil fuel Difficult to collect or grow large quantities It produce greenhouse gases 19 September 2018 A Massawe

Transformers Transformers are used in the National Grid to
from the wires during transmission. A transformer that increases the voltage is called a A transformer that decreases the voltage is called a e.g. adapters and rechargers for mobile phones and CD players. reduce energy losses step-up transformer step-down transformer 19 September 2018 A Massawe

Transformers The ratio between the voltages in the coils is the same as the ratio of the number of turns in the coils primary voltage = turns on primary secondary voltage turns on secondary This can also be written as: Vp/Vs = Np/Ns Step-up transformers have turns on the secondary coil than primary coil. Step-down transformers have turns on the secondary coil than the primary coil. more fewer 19 September 2018 A Massawe

Transformers A transformer has 20 turns on the primary and 400 on the secondary. What is the output voltage if the input voltage is 500V? Vp/Vs = Np/Ns Therefore Vs/Vp = Ns/Np Vs/500 = 400/20 Vs = 500 x (400/20) Vs= 10,000 Volts 19 September 2018 A Massawe

Current A current flows when an electric charge moves around a circuit – measured as the rate of flow of charge The current flowing through a component in a circuit is measured using an The units for current is ammeter amperes or A 19 September 2018 A Massawe

Potential difference (voltage)
A potential difference, also called voltage, across an electrical component is needed to make a current flow through it. Potential difference across a component in a circuit is measured using a The voltmeter must be connected in with the component. voltmeter parallel 19 September 2018 A Massawe

Power, current and potential difference
You can work out power using this equation: power (W) = voltage (V) × current (A) is a measure of how quickly energy is transferred. power voltage current 19 September 2018 A Massawe

Power and energy Power is a measure of how quickly energy is transferred. You can work out power using this equation: energy transformed power time A Massawe 19 September 2018

Paying for electricity
The amount of electrical energy transferred to an appliance depends on its power, and on the length of time it is switched on for The amount of mains electrical energy transferred is measured in kilowatt-hours (kWh). One unit is 1kWh energy transferred (kWh) = power (kW) × time (h) The cost of the electricity used is calculated using this equation: cost = power (kW) × time (hour) × cost of 1 kWh (pence) 19 September 2018 A Massawe

Saving energy (cost efficiency)
payback time = cost of energy-saving measure ÷ money saved each year e.g. Double-glazing might cost £2,500 and save £100 a year. What is the payback time? = 2,500 ÷ 100 = 25 years 19 September 2018 A Massawe

Saving energy (cost efficiency)
When buying an energy-saving device, it is important to consider the advantages and disadvantages. Some disadvantages would be: 1. initial cost 2. use of extra resources to manufacture new device 3. cost of disposal of old device. Some of the advantages would be: 1. cost efficiency 2. saving energy and resources. 19 September 2018 A Massawe

Energy transfer and efficiency
Forms of energy - Most Kids Hate Learning GCSE Energy Names Magnetic - energy in magnets and electromagnets Kinetic - the energy in moving objects. Also called movement energy Heat – also called thermal 19 September 2018 A Massawe

Light – also called radiant energy Gravitational potential – stored energy in raised objects Chemical – stored energy in fuel, foods and batteries Sound – energy released by vabrating objects 19 September 2018 A Massawe

Electrical – energy in moving or static electric charges Elastic potential – stored energy in stretched or squashed objects Nuclear – stored in the nuclei of atoms 19 September 2018 A Massawe

Energy transfers Different types of energy can be transferred from one type to another, e.g. of useful energy transfer 19 September 2018 A Massawe

Sankey diagrams Sankey diagrams summarise all the energy transfers taking place in a process. The thicker the line or arrow, the greater the amount of energy involved. 19 September 2018 A Massawe

Calculating efficiency
The efficiency of a device such as a lamp can be calculated using this equation: efficiency = useful energy transferred x energy supplied The efficiency of the filament lamp is (10 ÷ 100) × 100 = 10% - this means that 10% of the electrical energy supplied is transferred as light energy (90% is transferred as heat energy). The efficiency of the energy-saving lamp is (75 ÷ 100) × 100 = 75% - this means that 75% of the electrical energy supplied is transferred as light energy (25% is transferred as heat energy). 19 September 2018 A Massawe

P1 - Universal physics 19 September 2018 A Massawe.

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