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9.2. Potential difference and power
A subsection of Physics, 9702, through 9. Electricity
Listing 10 of 90 questions
Define the potential difference across a component. The variation with potential difference V of the current I in a semiconductor diode is shown in . 0.5 1.0 V / V I Use to describe qualitatively: the resistance of the diode in the range V = 0 to V = 0.25 V the variation, if any, in the resistance of the diode as V changes from V = 0.75 V to V = 1.0 V. A battery of electromotive force (e.m.f.) 12 V and negligible internal resistance is connected to a uniform resistance wire XY, a fixed resistor and a variable resistor, as shown in . 1.6 m 5.0 Ω 2.0 m 2.7 A 1.5 A W 12 V Z X Y resistance wire (not to scale) The fixed resistor has a resistance of 5.0 Ω. The current in the battery is 2.7 A and the current in the fixed resistor is 1.5 A. Calculate the current in the resistance wire. current = A Determine the resistance of the variable resistor. resistance = Ω Wire XY has a length of 2.0 m. Point Z on the wire is a distance of 1.6 m from point X. The fixed resistor is connected to the variable resistor at point W. Determine the potential difference between points W and Z. potential difference = V The resistance of the variable resistor is now increased. By considering the currents in every part of the circuit, state and explain whether the total power produced by the battery decreases, increases or stays the same.
9702_m23_qp_22
THEORY
2023
Paper 2, Variant 2
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State what is meant by an electric current. Define electric potential difference. The variation with potential difference V of the current I in a component Y and in a resistor R are shown in . 0.4 0.5 0.6 0.7 0.3 I / A 0.2 0.1 V / V component Y component Y component Y resistor R Use to explain how it can be deduced that resistor R has a constant resistance of 20 Ω. The component Y and the resistor R in are connected in parallel as shown in . E Y R 20 Ω A battery of e.m.f. E and negligible internal resistance is connected across the parallel combination. Use data from to determine the current in the battery for an e.m.f. E of 6.0 V, current = A the total resistance of the circuit for an e.m.f. of 8.0 V. resistance = Ω The circuit of is now re-arranged as shown in . E Y R The current in the circuit is 0.20 A. Use to determine the e.m.f. E of the battery. E = V Calculate the total power dissipated in component Y and resistor R. power = W
9702_s10_qp_23
THEORY
2010
Paper 2, Variant 3
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Questions Discovered
90