Physics · May / June 2020 · Paper 41 · Question 8
0625
As printed in the paper
The question as text
The power supply used in an electric vehicle contains 990 rechargeable cells each of electromotive force (e.m.f.) 1.2 V. The cells are contained in packs in which all the cells are in series with each other. The e.m.f. of each pack is 54 V.
Read automatically from the paper; the printed page above is exact.
Show the answer and mark scheme
8(a)[2]
990 / (54 / 1.2) OR 990 / 45 OR (number of cells in pack =) 54 / 1.2 OR 45
22
8(b)(i)[2]
(P =) EI OR 1.2 × 3.5
4.2 W OR 4.2 J / s
8(b)(ii)[3]
thick wires have a smaller resistance
less thermal energy generated in wires
more efficient OR less risk of fire / insulation melting
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