A high-voltage supply provides a constant potential difference of

PHYSICS · Subjective · A Level · Physics · Fields and their consequences · Fields and their consequences

Problem

500\,\text{V}

. It is required to build a capacitor bank that stores at most

8\,\text{J}

of energy at this voltage. Only capacitors of

8\,\mu\text{F}

each are available, and they may be connected exclusively in parallel. (i) Derive an expression that relates the number

n

of such capacitors to the maximum energy

W

that can be stored at a given supply voltage

V

when they are connected in parallel. (ii) Using the expression obtained in part (i), calculate the smallest integer

n

that will ensure the stored energy does not exceed

8\,\text{J}

500\,\text{V}

. (iii) For the number of capacitors found in part (ii), compute the total charge drawn from the supply when the bank is fully charged.