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Q2) A 120  capacitor is charged through a 4.7  resistor from a 12 V d.c. power supply.

(a) Calculate the instantaneous charging current at switch-on. (2)

(b) State the expression for the capacitor charging voltage and determine its value 2 seconds after switch-on. (4)

(c) Calculate the energy stored in the capacitor 2 seconds after switch-on. (2)

(d) After 2 seconds of charging the supply is switched off and the capacitor is discharged

through a 1.2  resistor.

(i) Determine the time taken during discharge for the capacitor voltage to fall to 5 V. (4)

(ii) Sketch a clearly labelled graph to show how a capacitor voltage changes over

charge/discharge cycle. (4)