Physics · May / June 2023 · Paper 41 · Question 7
0625
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The question as text
Fig. 7.1 shows a circuit that contains a battery, a switch, a voltmeter and three 40 Ω resistors, R1, R2 and R3. V R1 R3 R2 Fig. 7.1 The switch is open and resistors R1 and R2 form a potential divider.
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7(a)[2]
any two from:
(potential divider) splits / shares / divides the e.m.f. / voltage / potential difference / p.d. (of a power source / in a circuit) •
(e.m.f. is) split between (two) resistors / components (connected in series to power source)
(potential divider shares e.m.f.) in proportion to the resistances (of the resistors / components)
7(b)(i)[1]
(e.m.f. =) 15 V
7(b)(ii)[3]
(resistance =) 60 Ω
(Rll =) R2R3 / (R2 + R3) OR (Rll =) 40 × 40 / (40 + 40) OR (Rll =) 1600 / 80
OR 1 / Rll = 1 / R2 + 1 / R3 OR 1 / Rll = 1 / 40 + 1 / 40 OR (Rll =) (1 / 40 + 1 / 40)–1 OR (Rll =) 20 (Ω)
(resistance =) 40 + (candidate’s value for combined resistance of R2 and R3)
7(c)[2]
(reading =) 10 V
emf shared in same proportion as resistance
OR e.g. R1 / Rll = V1 / Vll
OR (reading =) 15 × 40 / 60 OR (reading =) 0.25 × 40
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