Presentation is loading. Please wait.

Presentation is loading. Please wait.

Concept 2 Energy Transfer. C ONCEPT 2 V OCABULARY T ERMS Static electricity Proton Electron Neutral Charge separation Electrical discharge Electrical.

Similar presentations


Presentation on theme: "Concept 2 Energy Transfer. C ONCEPT 2 V OCABULARY T ERMS Static electricity Proton Electron Neutral Charge separation Electrical discharge Electrical."— Presentation transcript:

1 Concept 2 Energy Transfer

2 C ONCEPT 2 V OCABULARY T ERMS Static electricity Proton Electron Neutral Charge separation Electrical discharge Electrical current Circuit Amperes (A) Conductors Load Voltage Potential difference Volt (V) Voltmeter Short circuit Insulators Fuses Circuit breakers

3 C ONCEPT 2 V OCABULARY T ERMS Electrochemical cell Dry cell Electrolyte Ion Electrode Wet cell Primary cell Rechargeable cell Secondary cell Battery Electrolysis Electrochemistry Electroplating

4 C ONCEPT 2 – V OCABULARY T ERMS Conductor Insulator Resistor Resistance Ohms ( Ω) Variable resistor Rheostat Ohm’s Law Ammeter Schematic Schematic diagram Series circuit Parallel circuit Transistor Microcircuit

5 C ONCEPT 2 – E NERGY T RANSFER Learning Concept Investigate and evaluate the use of different electrodes, electrolytes and electrolytic concentrations in designing electrical storage cells

6 C ONCEPT 2 – E NERGY T RANSFER Recall: Chemical energy is transformed into electrical energy in battery-powered devices An electrochemical cell is a device which has different metals in a solution containing a salt or acid

7 C ONCEPT 2 – E NERGY T RANSFER In an electrochemical cell, there are two metal electrodes surrounded by an electrolyte, a substance that can conduct electricity

8 C ONCEPT 2 – E NERGY T RANSFER Learning Concept Assess the potential danger of electrical devices, by referring to the voltage and current rating (amperage) of the devices Distinguish between safe and unsafe activities

9 C ONCEPT 2 – E NERGY T RANSFER Two aspects of electricity must be considered when looking electrical dangers Voltage The measure of how much energy is carried by each particle Ampere The rate at which an electrical current flows

10 org C ONCEPT 2 – E NERGY T RANSFER High voltage is more dangerous than low voltage Small voltages can kill if the shock carries a significant amount of amps The number of amps is more important than voltage when assessing potential danger

11 C ONCEPT 2 – E NERGY T RANSFER 50,000 V is more likely to kill than 10 V A passed through your body won’t likely be felt Current in the range of A to 0.02 A causes a painful shock and loss of muscle control Currents as low as 0.1 A can be fatal Electric eel can discharge 600 V at 1.0 A

12 C ONCEPT 2 – E NERGY T RANSFER Taser (stun) guns can carry up to 50,000 volts Can deliver up to 1,500 V to a person’s body Small current of to 0.03 amps

13 C ONCEPT 2 – E NERGY T RANSFER Electrical outlets in Canada deliver 120 volts of electricity A light bulb draws about 0.5A while a toaster pulls 5A Possible to suffer fatal shock from a household outlet

14 C ONCEPT 2 – E NERGY T RANSFER Science Log Make a list of 5 safety pointers for use with electrical devices (reference pg 285) ex. Do not use electrical devices when near or in water unless they are specially designed

15 C ONCEPT 2 – E NERGY T RANSFER Learning Concept Distinguish between static and current electricity Identify example evidence of each

16 C ONCEPT 2 – E NERGY T RANSFER Recall: The proton has a positive charge The electron has a negative charge Most objects have equal amounts of positive and negative charges, which makes them neutral

17 C ONCEPT 2 – E NERGY T RANSFER Charge separation occurs when charged objects are brought close to neutral objects

18 C ONCEPT 2 – E NERGY T RANSFER Rubbing the balloon on your hair transfers electrons (e - ) from your hair to the balloon Bringing the charged balloon to the wall repels the e - in the wall but attracts the protons

19 C ONCEPT 2 – E NERGY T RANSFER The Laws of Electrical Charges Opposite charges attract each other Like charges repel each other

20 C ONCEPT 2 – E LECTRICAL E NERGY Electrical discharge is observed as a spark Static energy does not flow in a current but can build up and discharge Electrons build up in your body Doorknob becomes positively charged as “your” electrons repel the doorknob electrons “Your” electrons are attracted to the doorknob’s protons

21 C ONCEPT 2 – E NERGY T RANSFER Van de Graaff generator ture=related

22 C ONCEPT 2 – E NERGY T RANSFER While static energy builds up and discharges, it does not flow continuously Electrical currents are steady flows of charged particles This is the type of energy used to operate electrical devices

23 C ONCEPT 2 – E NERGY T RANSFER Learning Concept Identify electrical conductors and insulators Compare resistance of different materials to electric flow

24 C ONCEPT 2 – E NERGY T RANSFER Insulators do not allow for easy transfer of electrons away from the nucleus Tightly bound to the nuclei

25 C ONCEPT 2 – E NERGY T RANSFER In a conductor the electrons are more loosely bound so they can move away from the nuclei Current will only flow if the conductor is hooked to an electrical source

26 C ONCEPT 2 – E NERGY T RANSFER Different materials conduct electricity at different abilities Important to know so devices designed are both safe and effective

27 C ONCEPT 2 – E NERGY T RANSFER A resistor is a type of conductor Allows current to pass but applies a resistance to it Limits amount of electric current to pass Resistance is a measure of how difficult it is for electrons to flow through a substance

28 C ONCEPT 2 – E NERGY T RANSFER Resistance is measured in ohms Symbol is the Greek letter omega,  The more resistance a substance has, the more energy is gained from each electron passing through it

29 C ONCEPT 2 – E NERGY T RANSFER A polygraph machine (lie detector) is an application of resistance Measures skin resistance, blood pressure and respiration

30 C ONCEPT 2 – E NERGY T RANSFER Learning Concept Use switches and resistors to control electrical flow Predict effect of these devices and others in an application

31 C ONCEPT 2 – E NERGY T RANSFER A switch is the best method for turning electricity on and off Basic principle: when on, two conductors are pressed together and electrons can flow When off, the conductors are not in contact, and electron flow is interrupted

32 C ONCEPT 2 – E NERGY T RANSFER A variable resistor, or rheostat, is used to increase or decrease the amount of current in a circuit slowly Dimmer light switch Volumes on stereos Foot-operated speed controls on sewing machines

33 C ONCEPT 2 – E NERGY T RANSFER Learning Concept Describe, using models, the nature of electric current Explain the relationship between current, resistance, and voltage

34 C ONCEPT 2 – E NERGY T RANSFER Recall: Current looks at how quickly an electrical charge is able to move ( amps ) Voltage looks at how much charge is carried in the electrical current ( volts ) Resistance is a measure of how difficult it is for electrons to transfer ( ohms )

35 C ONCEPT 2 – E NERGY T RANSFER

36 The hydo-flow model has several components Water in the container Amount of water pouring from the spouts Force of gravity on the water Diameter of the spout

37 C ONCEPT 2 – E NERGY T RANSFER Learning Concept Measure voltages and amperages in circuits Apply Ohm’s law to calculate resistance, voltage and current in simple circuits

38 C ONCEPT 2 – E NERGY T RANSFER German scientist Georg Simon Ohm proved a mathematical link between voltage (V), current (I) and resistance (R)

39 C ONCEPT 2 – E NERGY T RANSFER Ohm’s law states that as long as temperature remains the same Resistance of a conductor stays the same Current is directly proportional to the voltage applied

40 C ONCEPT 2 – E NERGY T RANSFER So long as two of the three units are known, the last one can be solved for

41 C ONCEPT 2 – E NERGY T RANSFER Ohm’s Law QuantitySymbolUnitEquationMeasured with … VoltageVvolts (V) Voltmeter CurrentIamps (A) Ammeter ResistanceRohms  Ohmmeter

42 C ONCEPT 2 – E NERGY T RANSFER Example An electrical stove is connected to a 240-V outlet. If the current flowing through the stove is 20-A, what is the resistance of the heating element?

43 C ONCEPT 2 – E NERGY T RANSFER Example A 30-V battery creates a current through a 15- Ω resistor. How much current is created?

44 C ONCEPT 2 – E NERGY T RANSFER Example A motor has an internal resistance of 40-Ω. The motor is in a circuit with a current of 4.0-A. What is the voltage?

45 C ONCEPT 2 – E NERGY T RANSFER Example A current of 625-mA runs through a bulb that is connected to 120-V. What is the resistance of the bulb?

46 C ONCEPT 2 – E NERGY T RANSFER Learning Concept Develop, test and troubleshoot circuit designs for a variety of specific purposes

47 C ONCEPT 2 – E NERGY T RANSFER A circuit is simply a complete path that charged particles can flow through Often drawn with symbols in an image known as a schematic or a schematic diagram

48 C ONCEPT 2 – E NERGY T RANSFER Using your textbook as a reference (pg 312) complete the following diagram of electrical symbols SymbolRepresentsDescription Conductor Cell Battery Lamp Resistor Switch Ammeter Voltmeter Rheostat Motor Fuse

49 C ONCEPT 2 – E NERGY T RANSFER A series circuit is one in which the current passes through each bulb in turn

50 C ONCEPT 2 – E NERGY T RANSFER Disadvantages If the pathway is interrupted the whole circuit cannot function Adding components increases the total resistance Adding another bulb would make all the lights dimmer

51 C ONCEPT 2 – E NERGY T RANSFER Advantages Household circuits are wired so that it is possible to turn off all the electricity in the circuit

52 C ONCEPT 2 – E NERGY T RANSFER Parallel circuits have separate current paths for each section of the circuit Each bulb would have its own path to the current source

53 C ONCEPT 2 – E NERGY T RANSFER Advantages An interruption or break in one pathway does not affect the rest of the pathways Adding extra resistors decreases the total resistance in the circuit

54 C ONCEPT 2 – E NERGY T RANSFER Learning Concept Identify similarities and differences between microcircuits and circuits in a house

55 C ONCEPT 2 – E NERGY T RANSFER Define transistor Define fuse Use page 315 of your textbook to compare and contrast microcircuits and household wiring


Download ppt "Concept 2 Energy Transfer. C ONCEPT 2 V OCABULARY T ERMS Static electricity Proton Electron Neutral Charge separation Electrical discharge Electrical."

Similar presentations


Ads by Google