 # Twenty Questions Electricity 1. Twenty Questions 12345 678910 1112131415 1617181920.

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Twenty Questions Electricity 1

Twenty Questions 12345 678910 1112131415 1617181920

1. State the relationship for current in a Series circuit. Current is the same at all points in a series circuit. I 1 = I 2 = I 3

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

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

4. Calculate the total resistance. 10Ω 20Ω 5Ω5Ω

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

6. Calculate the power dissipated in a 330 Ω resistor when a 5A current flows through it. P = I 2 R P = (5) 2 x 330 P = 8250W

7. Two identical 10Ω resistors are connected to a 9V supply. What is the current through each resistor? R = 10 + 10 = 20Ω I=V/R=9/20 I = 0.45A

8. State the relationship for voltage in a parallel circuit. Voltage in a parallel circuit is equal across each branch. V T = V 1 = V 2 = V 3

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

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

11. Which resistor has a greater potential difference across it? The 7 Ω resistor. 9V 7Ω7Ω 6Ω6Ω

12. Calculate the voltage across the resistor. V s = V 1 + V 2 12 = 4 + V 2 V 2 = 8V 12V 4V

13. What is current? The rate of flow of electric charges around a circuit. The charge per second that passes a point.

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

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

16. What is the current through the bulb? I T = I 1 + I 2 4 = 3 + I 2 I 2 = 1A 4A 3A

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

18. Calculate the energy used by a 12V kettle in 2minutes if it draws 3A from it’s supply. P = IV = 3x12 = 36W E = Pt E = 36x2x60 E = 4320J

19. What formula relates power, voltage and resistance? P = V 2 /R

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

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