9. (b) A capacitor is connected to a switch, a battery and a bulb as shown in the diagram.
When the switch is moved from position A to position B, the bulb lights briefly.
(i) What happens to the capacitor when the switch is in position A?
(iii) When the switch is in position A the capacitor has a charge of 0.6 C. Calculate its capacitance.
(iv) Give a use for a capacitor. (C = Q/V)
A input B C
12. (d) The diagram shows a transformer. (i) Name the parts labelled A and B.
(ii) The input voltage is 230 V. Part B has 4600 turns and part C has 120 turns. Calculate the output voltage.
output
(iii) Name a device that uses a transformer. (Vi / Vo = Np /Ns)
Higher Level 2010
12. (d) The diagram shows a negative charge of 2 μC, positioned 25 cm away from a positive charge of 5 μC.
10 cm P 15 cm –2 C5 C
Copy the diagram and show on it the direction of the electric field at point P.
Calculate the electric field strength at P.
Under what circumstances will point discharge occur? (permittivity of free space = 8.9 × 10–12 F m–1)
2009
9. A 64 μF capacitor in a defibrillator is charged to a potential difference of 2500 V.
The capacitor is discharged through electrodes attached to the chest of a heart attack victim. Calculate: (i) the charge stored on each plate of the capacitor (ii) the energy stored in the capacitor
(iii) the average current that flows through the victim when the capacitor discharges in a time of 10 ms
(iv) the average power generated as the capacitor discharges. 320 FUSION (30)
(15) (4)
(18) (6) (ii) Why does the bulb light when the switch is in position B? (6)
