10.2. Kirchhoff’s laws
A subsection of Physics, 9702, through 10. D.C. circuits
Listing 10 of 93 questions
Distinguish between potential difference (p.d.) and electromotive force (e.m.f.) in terms of energy transformations. Two cells A and B are connected in series with a resistor R of resistance 5.5 Ω, as shown in . R 5.5 Ω 4.4 V 2.3 Ω cell A 2.1 V 1.8 Ω cell B Cell A has e.m.f. 4.4 V and internal resistance 2.3 Ω. Cell B has e.m.f. 2.1 V and internal resistance 1.8 Ω. State Kirchhoff’s second law. Calculate the current in the circuit. current = A On , draw an arrow to show the direction of the current in the circuit. Label this arrow I. Calculate 1. the p.d. across resistor R, p.d. = V 2. the terminal p.d. across cell A, p.d. = V 3. the terminal p.d. across cell B. p.d. = V
9702_w11_qp_23
THEORY
2011
Paper 2, Variant 3
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A battery of electromotive force (e.m.f.) 12 V and negligible internal resistance is connected to a network of two lamps and two resistors, as shown in . 0.50 A 12 V 0.20 A X R 28 Ω Y The two lamps in the circuit have equal resistances. The two resistors have resistances R and 28 Ω. The lamps are connected at junction X and the resistors are connected at junction Y. The current in the battery is 0.50 A and the current in the lamps is 0.20 A. Calculate: the resistance of each lamp resistance = Ω resistance R. R = Ω Determine the potential difference VXY between points X and Y. VXY = V Calculate the ratio total power dissipated by the lamps total power produced by the battery . ratio = The resistor of resistance R is now replaced by another resistor of lower resistance. State and explain the effect, if any, of this change on the ratio in .
9702_w19_qp_23
THEORY
2019
Paper 2, Variant 3
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State Kirchhoff’s second law. Three identical cells, each of electromotive force (e.m.f.) 1.5 V and internal resistance 590 mΩ, are connected in parallel across a conductor, as shown in . 1.5 V 590 mΩ 1.5 V 590 mΩ 1.5 V 590 mΩ A B conductor The conductor is composed of two cylindrical sections A and B. The total resistance of the circuit is 2.2 Ω. Show that the resistance of the conductor is 2.0 Ω. Calculate the current in the conductor. current = A The two cylindrical sections A and B of the conductor in are made from the same material and have the same length. The diameter of section A is 4.3 mm and the diameter of section B is 7.6 mm. The resistance of section A is RA and the resistance of section B is RB. Calculate the ratio RA RB . RA RB = Calculate the ratio average drift speed of free electrons in section A average drift speed of free electrons in section B . Explain your reasoning. ratio = The circuit of is altered by removing one of the cells. State and explain the effect, if any, of this change on the potential difference across the conductor.
9702_w22_qp_23
THEORY
2022
Paper 2, Variant 3
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Questions Discovered
93