O-LevelPhysicsElectricity5054/22 · Oct/Nov 2021 · Q55 Marks
EITHER Fig. 5.1 shows a circuit that contains a direct current (d.c.) power supply, a light-dependent resistor (LDR), two fixed resistors, M and N, and two ammeters. [Figure 5.1]
- (a)The reading on ammeter 1 is 1.6 mA. Calculate the time taken for a charge of 7.2C to pass through ammeter 1. time =[2]
- (b)(i)Some time later, the brightness of the light incident on the LDR decreases. Explain what happens to: (i) the reading on ammeter 2[1]
- (b)(ii)the time taken for a charge of 7.2C to pass through ammeter 1.[2]
This question uses a diagram from the original paper, which isn't shown here. Open the full paper from the past papers archive to see it.
Mark scheme
Marking points from the official mark scheme (Oct/Nov 2021). The mark or mark type is shown in brackets.
- [C1] (t =) Q/ I or 7.2/0.0016 or 7.2 / 1.6 or 4.5 × 10N
- [A1] 4500 s
- [B1] does not change and p.d. / voltage across resistor N does not change / ammeter 2 is not in the branch that contains the LDR
- [B1] resistance of LDR increases or current (in M / in ammeter 1) decreases
- [B1] time taken increases
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