Electricity

The following topic has been broken down into components. Click on the part you wish to learn about in more detail below.

Electricity TransferMeasuring Electricity
Ohm’s LawUses of Electricity
Efficiency of ElectricityFuture of Electricity
Van de GraaffSources of Electricity

Topic Revision

1. Define the following terms:

  1. current
  2. voltage
  3. resistance
  4. insulator
  5. conductor
  6. electron
  7. ampere
  8. ohm
  9. volt
  10. fossil fuel
  11. renewable

2. Draw the symbols used to represent the following in a circuit diagram:

  1. light bulb
  2. battery
  3. wire
  4. switch
  5. transformer
  6. resistor
  7. voltmeter
  8. ammeter

3.         a) What are ammeters and voltmeters used for?

            b) How should each of them be connected in a circuit?

c) Draw a circuit diagram showing a 4W resistor connected to a double cell battery. Indicate on your diagram where you would wire in an ammeter and voltmeter.

4.         a) What is the difference between series and parallel circuits?

b) Draw two circuits- one with 2 globes connected in series and the other with 2 globes connected in parallel.

5. Draw each of the following circuits:

  1. A transformer/powerpack connected to a switch and 3 globes in series.
  2. A transformer/powerpack connected to 2 globes in series, connected to a third in parallel.
  3. 3 globes connected in parallel that can be turned on and off independently.

6. Draw a table showing the advantages and disadvantages of both series and  

   parallel circuits.

7. Use the analogy of moving water to explain a switch, current and potential difference.

8. Complete the following table using Ohm’s Law (V=I x R).

Current (I)Voltage (V)Resistance (R)
6A12V 
3A75.6V 
 2.6V42W
 1.8V6.5W
4.2A 12.9W
43mA 0.6W

9. Describe the Law of Conservation of Energy. What does this mean?

10. Draw a diagram showing the energy changes in:

a) An incandescent light bulb

b) A radio

c) An electric stove

11. Is all the energy used productively in these devices?

12. Describe how we can calculate the energy efficiency of an appliance. Why is this important for you and society as a whole?

13. An oven consumes 425 kWh of energy in order to provide 386 kWh of useful energy. What is its percent efficiency?

14. How do you make an electromagnet?

15. Describe how most electricity is generated at present. What are the problems caused by this? (think about how it is obtained and the products from its burning)

16. Describe one alternative method for generating electricity other than burning fossil fuels. Outline both the advantages and disadvantages of using this method.

17. Construct a line graph to show the relationship between current and voltage. Place current on the x axis and voltage on the y axis (opposite what we usually do, but it matches up better with ohms law)

Voltage (V)Current (A)
00
10.5
21
31.5
42
52.5
63

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