1. St Columba’s High School Electricity and Electronics Capacitors

2. The ‘coulomb per volt’ is a unit of 1.Charge 2.Energy 3.Capacitance 4.Potential difference :30

3. Capacitors store 1.Current 2.Charge 3.Voltage 4.Power :30

4. Capacitors 1.Block a.c. but pass d.c 2.Block d.c and a.c. 3.Block d.c. but pass a.c. :30

5. An 8 μF capacitor requires 1.1 μ C to charge it to 1 V 2.8 μC to charge it to 8 V 3.8 μC to charge it to 1 V 4.8 C to charge it to 8 μV :90

6. What does the shaded area under the graph represent ? 1.The capacitance of the capacitor 2.The working voltage of the capacitor 3.The charge stored on the plates of the capacitor 4.The energy stored in the capacitor :30

7. What is represented by the gradient of the graph shown ? 1.The energy stored by the capacitor 2.The capacitance of the capacitor 3.The charge stored 4.The Current flowing :30

8. A 500 μF capacitor has a potential difference of 20 V across it. The charge stored is 1.10 μC 2.10 mC 3.50 mC 4.0.04 μC :90

9. The energy stored in a 500 μF capacitor charged to a voltage of 20 V is : :90 1.0.005 J 2.0.05 J 3.0.01J 4.0.1 J

10. A resistor,R, and a capacitor,C are connected in series.Which graphs are correct for the capacitor charging up ? 1.A 2.B 3.C 4.D ABCDABCD :30

11. As the frequency of the supply is increased from 50 to 5000 Hz the reading on the ammeter will : 1.Remain constant 2.Decrease steadily 3.Increase then decrease 4.Increase steadily :30

12. The maximum value of the current flowing is : 1.0 A 2.0.5 mA 3.0.5 A 4.0.005 mA :90

13. If the resistance is increased what happens to the time it takes for the capacitor to charge ? 1.Increases 2.Stays the same 3.Decreases :30

14. A 25 μF capacitor is charged until the pd across it is 500 V. Calculate the charge stored. 1. 5.00 x 10 -8 C 2.2.00 x 10 -5 C 3.1.25 x10 -2 C 4.1.25 x 10 -4 C :90

15. Calculate the energy stored when the pd across the capacitor is 10 V. 1.0.4 mJ 2.2.5 mJ 3.10 mJ 4.20 mJ :90

16. Which answer describes what happens to the bulbs as the frequency is increased but the output voltage remains constant ? 1.P brighterQ unchanged 2.P unchangedQ brighter 3.P dimmerQ unchanged 4.P unchangedQ dimmer :30