# CIE AS & A Level Physics : 10.3 Potential dividers – Exam style question – Paper 1

### Question

A cell has an electromotive force (e.m.f.) of 8.0V and negligible internal resistance. The cell forms part of a circuit, as shown. The reading $$V_{1}$$ is 4.0V and the reading $$V_{2}$$ is also 4.0V.

What is the resistance of resistor R?

A    $$0.50\, \Omega$$          B    $$2.0\, \Omega$$              C    $$4.0\, \Omega$$             D    $$8.0\, \Omega$$

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### Question

Three identical cells, each of electromotive force (e.m.f.) E and internal resistance r, are connected as shown. What is the potential difference between points X and Y?
A 0                     B E                      C 2E                   D 3E

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### Question

Potential differences across two resistors of resistances R1 and R2 are compared using a potentiometer wire (uniform resistance wire) in the electrical circuit shown. One terminal of a galvanometer is connected to point X. The galvanometer reads zero when its other terminal is connected to a point that is a distance of 60 cm from one end of thepotentiometer wire.One terminal of a second galvanometer is connected to point Y. This galvanometer reads zerowhen its other terminal is connected to a point that is a distance of 80 cm from the same end of the potentiometer wire.
What is the ratio  $$\frac{R_{2}}{R_{1}}$$

A $$\frac{1}{3}$$            B $$\frac{3}{4}$$            C $$\frac{3}{1}$$            D $$\frac{4}{3}$$

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### Question

A battery is connected to a potentiometer. The potentiometer consists of a uniform resistance
wire and a sliding contact P. The potential difference (p.d.) V between the sliding contact P and end Q of the wire is measured
using a voltmeter. The sliding contact P is moved from end Q to end R of the wire. Sliding contact
P is distance d from Q.
Which graph shows the variation with distance d of the p.d. V? Ans

### Question

A potentiometer circuit is used to determine the unknown electromotive force (e.m.f.) of a cell X.
In the circuit shown, E is a cell with an e.m.f. that is known accurately. QR is the potentiometer
wire, which has a movable contact S. Contact S is connected to a galvanometer and to cell X. What is not a necessary requirement to determine the e.m.f. of X from the circuit?
A     The e.m.f. of cell X must be lower than the e.m.f. of cell E.
B    The internal resistance of cell X must be known.
C    The lengths QS and QR must be determined accurately.
D    The resistance of the wire QR must be proportional to its length.