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Twenty Questions

Electricity 2

Twenty Questions

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1. Give 1 advantage of using a circuit breaker.

• Reset instead of replaced.• Easier to see if it’s off.

2. What type of appliance uses the greatest power?

• One which produces heat.

3. Upon what does the size of an appliances flex depend?

• It’s power rating.

4. In a house in what configuration are the wiring circuits? Why?

• Parallel.•So each appliance can be switched on/off separately.•Each appliance will have 230V across it.

5. A heater has a current of 6A flowing through it for 4 minutes, what charge will pass through it.

•Q = It = 6 x (4 x 60) = 1440 C

6. Draw the electrical field surrounding a negative point charge.

7. State Ohm’s Law

• R = V ÷ I

8. Draw the symbol for a fuse.

• Rectangle with the wire passing through it.

9. Give an example each of a d.c. and an a.c. power source.

• d.c – battery• a.c - mains.

10. If a heater uses 1500 J of energy each second, What current will it draw if it is working from the mains voltage?•V = 230V• P = 1500W as P = E / t •I = P ÷ V = 1500 ÷ 230 = 6.5 A

11. Calculate the current in a circuit if 135 charges take 3minutes to travel through the circuit.

• Q = I t t = 3x60 =180s I = Q/t • I = 135/180 • I = 0.75A

12. What are the values of the voltage and frequency of the mains supply?

•230V

•50Hz

13. What is current?

•The flow of electric charges around a circuit.

13. What is current?

•The flow of electric charges around a circuit.

14. What are the units for charge?

• Coulombs

15. What type of energy is gained when work is done moving a charge between two plates?

• Kinetic

16. What danger is present when using a multiway adapter?

•If too many appliances are used or ones which require much current are used it may overheat and catch fire.

17. Calculate the number of electrons that pass through a wire carrying a current of 2 A for 5 s. Qelectron = 1.6x10-19 C

• Q = It• = 2 x 5• = 10CNo. of electrons =10 ÷ 1.6x10-19

= 6.25 x 1019

18. What type of current is shown by the waveform?

• a.c / alternating current

19. Why must the fuse value be greater than the current used by the appliance?

• It melts when it’s rating/value has been reached

20. What fuse would be used in a 2kW kettle?

• I=P/V• I=2000/230• I=8.7A• 13A fuse.