2024 · M/J · 9702/41 | Q7

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Question (7 of 10)8 marks · Practise this topic →

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Available practice: 94 of 100 marks. Parts 3(a)(i), 7(a), 8(a) await marking support. Scores cover available parts only.

A sinusoidal alternating supply is connected to a bridge of four diodes with a load resistor R across the output . Fig. 7.2 shows the variation of V_OUT with time t.

(b)(i)The load resistor R has a resistance of 370 Ω. Show that the maximum power dissipated in R is 0.22 W.

Fig. 7.1 — see the question text for what it shows

Fig. 7.2 — see the question text for what it shows

Answer guidance

Show The result is given, so every step of the reasoning is what earns the marks.

[2 marks]

A sinusoidal alternating supply feeds a bridge rectifier with load resistor R of resistance 370 Ω; the rectified output voltage V_OUT has a peak value of about 9.0 V and touches zero every 0.02 s over the interval t = 0 to 0.08 s . The maximum power dissipated in R is 0.22 W.

(b)(ii)On Fig. 7.3, sketch the variation with t of the power P dissipated in R.

Fig. 7.3 — see the question text for what it shows

[3 marks]

A sinusoidal alternating supply feeds a bridge rectifier with a load resistor R of resistance 370 Ω. The maximum power dissipated in R is 0.22 W.

(b)(iii)Calculate the mean power dissipated in R.

Answer guidance

Calculate Show your working. The method can earn marks even when the final value is wrong, and a bare answer often cannot.

[1 mark]

A sinusoidal alternating supply feeds a bridge rectifier circuit with a load resistor R of resistance 370 Ω, and the mean power dissipated in R has been calculated. The circuit of Fig. 7.1 is now disconnected, and R is connected directly across the power supply.

(c)Explain, without calculation, how the mean power now dissipated in R compares with the answer in (b)(iii).

Answer guidance

Explain Give reasons, not just what happens. Each distinct reason is usually worth a mark.

[2 marks]

9702/41/M/J/24Cambridge International AS & A Level Physics 9702 · May/June 2024 · Paper 4 variant 1 · Question 7