A-Level PhysicsYear 2020Q15
14 15 The properties of capacitors make them useful in timing circuits. The following circuit is used to provide an input Y to an integrated circuit. 8.0 V 0 V Y integrated circuit C = 1.5 μF S2 R2 = 2.7 kΩ S1 R1 = 3.3 kΩ (a) Initially the capacitor is uncharged. The switch S1 is closed. Sketch a graph to show how the potential at point Y varies with time. (3) .................................................................................................................................................................................................................................................. .................................................................................................................................................................................................................................................. Potential / V 10 20 30 Time / ms 15 Turn over (b) When the potential at Y is 8.0 V, the switch S2 is closed. (i) Calculate the time taken for the potential at Y to decrease to 2.0 V. (3) .................................................................................................................................................................................................................................................. .................................................................................................................................................................................................................................................. .................................................................................................................................................................................................................................................. .................................................................................................................................................................................................................................................. Time taken = ...................................................... (ii) Calculate the energy stored on the capacitor when the potential at Y is 2.0 V. (2) .................................................................................................................................................................................................................................................. .................................................................................................................................................................................................................................................. .................................................................................................................................................................................................................................................. .................................................................................................................................................................................................................................................. Energy stored = ...................................................... (c) When the potential at Y is 2.0 V, the switch S2 is opened. Calculate the power dissipated by the resistance R1 when the potential at Y is 2.0 V. (3) .................................................................................................................................................................................................................................................. .................................................................................................................................................................................................................................................. .................................................................................................................................................................................................................................................. .................................................................................................................................................................................................................................................. .................................................................................................................................................................................................................................................. .................................................................................................................................................................................................................................................. Power dissipated = ...................................................... (Total for Question 15 = 11 marks)
Paper Source:9PH0_01_que_20201010.pdf
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Exam Specification Info
This question is part of the UK A-Level Physics syllabus. In the actual exam, structured questions typically require linking specific keywords to gain full marks. Applaa helps you drill these topics.
Syllabus levelAdvanced Level (A-Level)
SubjectPhysics
Official MarksVariable (2–6 marks)
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