1. St Columba’s high School Electricity and Electronics Electric Fields and Resistors in Circuits Alternating Current and Voltage

2. Which of the following statements is/are correct? A. There is a force on a charge in an E-field. B. When an E-field is applied to a conductor, free charges move through it. C. Work is done when a charge is moved in an E-field. 1.A only 2.B only 3.A and C only 4.B and C only 5.A, B and C 30

3. One Volt is……. 1.One Joule Coulomb 2.One Coulomb per Second 3.One Joule per Coulomb 4.One Joule per Second 5.One Coulomb per Joule 30

4. Metal parallel plates X and Y are connected to a 3.0 V d.c. supply as shown. What is the gain in electrical potential energy of an electron moving between the plates? 3.0V Plate X Plate Y 90 1.1.6 x 10 –19 J 2.4.8 x 10 –19 J 3.9.6 x 10 –19 J 4.1.9 x 10 19 J 5.5.3 x 10 –20 J

5. Two parallel metal plates X and Y in a vacuum have a potential difference V across them. What is the speed of an electron of charge e and mass m as it reaches Y from X? V XY - + 90 1.2eV/m 2.√ 2eV/m 3.√2V/em 4.2V/em 5.2mV/e

6. In the circuit below, when the switch is open V = 2.6V. With the switch closed, V= 2.2V. This decrease of 0.4 V is called… V 30 1.Peak voltage 2.e.m.f. 3.r.m.s voltage 4.Lost volts 5.Terminal potential difference

7. The battery in the circuit below has an emf of 6.0V and an internal resistance of 0.20 ohms. What is the resistance of R if the reading on the ammeter is 4A? 1.1.5 ohms 2.2.2 ohms 3.1.3 ohms 4.0.7 0hms 5.6.4 ohms A 6.0V 0.20  R 90

8. What is the p.d. across the 10  resistor? 1.1.0V 2.1.2V 3.4.8V 4.5.0V 5.6.0V A 6.0V 2  10  90

9. The p.d. across the 16 ohm resistor is 40V when the switch is open. What is the p.d. across the 16 ohm resistor when S is closed? 8  16  S 8  60V 1.12V 2.15V 3.30V 4.45V 5.48V 90

10. In the circuit below, each resistor has a resistance of 20 ohms. What is the voltage across XY? 3.5V XY 1.3.5V 2.0.2V 3.2.0V 4.0.5V 5.1V 90

11. In the circuit shown, the p.d. between points P and Q is 12 V. What is the reading on the voltmeter? 1.0 V 2.2 V 3.4 V 4.6 V 5.8 V Q V P 22 44 88 44 30

12. In the Wheatstone bridge shown, there is a small reading on the voltmeter. What should be done to balance the bridge? 90 1.Increase P by 6  2.Increase Q by 6  3.Increase R by 6  4.Increase S by 6  5.Insert a 6  resistor in series with the voltmeter. 66 12  V P 44 Q R S

13. What is the total power developed in the circuit below? 12V 6  90 1.12W 2.24W 3.48W 4.300W 5.1200W

14. In the circuit below, the frequency of the a.c. supply output is varied in frequency from 50Hz to 5kHz. What is the ammeter reading? 1.Falls steadily 2.Remains constant 3.Rises then falls 4.Rises steadily 5.Falls then rises A 1K  30

15. A supply with alternating output 6V r.m.s. is connected as shown. What is the peak voltage across the resistor and the peak current in the circuit? 90 3  6V 1.Vp=6√2 Ip=2√2 2.Vp=6√2 Ip=2 3.Vp=6 Ip=2 4.Vp=6√2 Ip=1/(2√2) 5.Vp=6 Ip=2√2

16. The resistance of the LDR decreases when the light intensity increases. Which row shows the correct voltmeter readings when the lights are off? 1.V 1 = increases V 2 = increases 2.V 1 = decreases V 3 = increases 3.V 2 = increases V 3 = decreases 4.V 2 = no change V 3 = decreases 5.V 1 = decreases V 2 = no change - + V2V2 V V1V1 V3V3

17. The peak voltage of a supply is 70V. What is the r.m.s. value? 1.99.0V 2.35.0V 3.17.5V 4.49.5V 5.50.3V 90

18. A student measures the frequency of an a.c. supply and obtains the trace below. If the grid has 1cm squares, what is the frequency of the supply? Y-gain = 3mV/cm Timebase = 2ms/cm 1.0.06Hz 2.0.17Hz 3.41.7Hz 4.62.5Hz 5.125Hz 90