1. Twenty Questions
Electricity 1

2. Twenty Questions 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

3. 1. State the relationship for current in a Series circuit.
Current is the same at all points in a series circuit.

4. As resistance increases.
2. What effect does increasing the resistance of a circuit have on the current?
As resistance increases.

5. 3. In which position is the voltmeter/ammeter?A V

6. 4. Calculate the total resistance.
10Ω
20Ω 5Ω
4. Calculate the total resistance.

7. 5. Two identical bulbs are connected to a 9V battery
5. Two identical bulbs are connected to a 9V battery. What is the voltage across each bulb?
9/2= 4.5V

8. 6. Calculate the power dissipated in a 330Ω resistor when a 5A current flows through it.
P = I2 R
P = (5)2 x 330
P = 8.25kW

9. 7. Two identical 10Ω resistors are connected to a 9V supply
7. Two identical 10Ω resistors are connected to a 9V supply. What is the current through each resistor?
I=V/R=9/(10+10)
I = 0.45A

10. 8. State the relationship for voltage in a parallel circuit.
Voltage in a parallel circuit is equal across each branch.

11. 9. What is electrical power?
The rate at which electrical energy is converted to other forms.

12. 10. What is the function of a variable resistor?
To allow you to vary the current in a circuit.

13. 11. Which resistor has a greater potential difference across it?
The 7Ω resistor. 9V 7Ω 6Ω

14. 12. Calculate the voltage across the resistor.
Vs = V1 + V2
12 = 4 + V2
V2 = 8V

15. The flow of electric charges around a circuit.
13. What is current?
The flow of electric charges around a circuit.

16. The resistance of a resistor remains constant.
14. What happens to the value of a resistor when the Voltage across it is increased?
The resistance of a resistor remains constant.

17. 15. Give a practical application of a variable resistor.
Volume control on radio
Temperature control on cooker
Brightness control on a dimmer switch

18. 16. What is the current through the resistor?
IT = I1 + I2
4 = 3 + I2
I2 = 1A

19. 17. What is the total resistance of a 20Ω & 30 Ω resistor in parallel?

20. E = Pt P = IV = 3x12 = 36W E = 36(2x60) E = 3.84kJ
18. Calculate the energy used by a 12V kettle in 2minutes if it draws 3A from it’s supply.
E = Pt
P = IV = 3x12 = 36W
E = 36(2x60)
E = 3.84kJ

21. 19. What formula relates power, voltage and resistance?
P = V2/R

22. The energy given to each charge in the circuit.
20. What is Voltage?
The energy given to each charge in the circuit.