Page 189 - Physics Coursebook 2015 (A level)

Chapter 12: Practical circuits
7 Figure 12.14 shows a potentiometer circuit. Eo = 2.2 V
l
AB
V
Figure 12.14 For End-of-chapter Question 7.
a i
Sketch a graph of the reading on the voltmeter against I as the jockey is moved from point A
jockey uniform resistance wire
to point B. [2]
ii State the readings on the voltmeter when the jockey is connected to A and when it is connected
to B. (You may assume that the driver cell has negligible internal resistance.) [1]
iii Drawacircuitdiagramtoshowhowthepotentiometercouldbeusedtocomparethee.m.f.sof
two batteries. [3]
b When a pair of 4 Ω resistors are connected in series with a battery, there is a current of 0.60 A current
through the battery. When the same two resistors are connected in parallel and then connected
across the battery, there is a current of 1.50 A through it. Calculate the e.m.f. and the internal resistance
of the battery. [4]
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