1a
2 marks
2 marksSketch the circuits symbols for
(i)
the potentiometer
[1]
(ii)
the galvanometer
[1]
1b3 marks
3 marksFig. 1.1 shows a circuit with a potentiometer.
Fig. 1.1
Fixed ends AC are connected across the battery so that there is a full battery voltage across the whole resistor.
State the voltage output, Vout when the sliding connect is at
(i)
A
[1]
(ii)
B
[1]
(iii)
C
[1]
1c2 marks
2 marksThe resistor is now replaced with a uniform resistance wire connected between ends AC, as shown in Fig. 1.2a. The 28 V cell is replaced with a cell of unknown e.m.f.
Fig. 1.2a
Sketch a graph of Fig 1.2b to show the voltmeter reading V against length l as the jockey is moved from point A to point C.
Fig 1.2b
1d4 marks
4 marksA potentiometer can be used to compare e.m.fs of cells or potential differences.
A test cell is added to the circuit in Fig. 1.2a. A student sets up the circuit shown in Fig. 1.3.
Fig. 1.3
(i)
State why the student will not be able to find a point where the current is zero.
[1]
(ii)
The student fixes the issue from (a)(i) and achieves a balance point when the length of the wire AB is 25.6 cm.
They repeat the experiment with a standard cell of e.m.f 1.545 V. The balance point using this cell is 37.2 cm.
Calculate the e.m.f of the test cell.
[3]
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