9.2. Potential difference and power
A subsection of Physics, 9702, through 9. Electricity
Listing 10 of 90 questions
The diagram shows a battery of electromotive force (e.m.f.) 6 V, connected in series with a resistor and a uniform resistance wire RQ of length 60 cm. The resistance of RQ is equal to the resistance of the resistor. 6 V X R L Q Y P Terminal X is connected to fixed point R. Terminal Y is connected to point P, a connection that may be made at any position along the wire. L is the distance between R and P. Which graph shows the variation with L of the potential difference (p.d.) V across XY?
9702_w18_qp_11
MCQ
2018
Paper 1, Variant 1
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Define electric potential difference (p.d.). A wire of cross-sectional area A is made from metal of resistivity ρ. The wire is extended. Assume that the volume V of the wire remains constant as it extends. Show that the resistance R of the extending wire is inversely proportional to A2. A battery of electromotive force (e.m.f.) E and internal resistance r is connected to a variable resistor of resistance R, as shown in . A R E r I The current in the circuit is I. Use Kirchhoff’s second law to show that R = (E – r. An ammeter is used in the circuit in to measure the current I as resistance R is varied. is a graph of R against 1 I. –2 R / Ω / A–1 I 0.1 0.2 0.3 0.4 0.5 Use to determine the power dissipated in the variable resistor when there is a current of 2.0 A in the circuit. power = W Use and the equation in to: 1. state the internal resistance r of the battery r = Ω 2. determine the e.m.f. E of the battery. E = V
9702_w20_qp_23
THEORY
2020
Paper 2, Variant 3
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Questions Discovered
90