Physics (AS & A Level) · May / June 2016 · Paper 23 · Question 6
9702
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6(a)[1]
ohm is volt per ampere or volt / ampere [1]
6(b)(i)[3]
R = ρl / A RP = 4ρ(2l) / πd2 or 8ρl / πd2 or RQ = ρl / πd2 or ratio idea e.g. length is halved hence R halved and diameter is halved hence R is 1/4 RQ (= 4ρl / π4d2) = ρl / πd2 = RP / 8 (= 12 / 8) = 1.5 Ω [3]
6(b)(ii)[3]
power = I 2R or V 2 / R or VI = (1.25) 2 × 12 + (10) 2 × 1.5 or (15) 2/12 + (15) 2/1.5 or 15 × 11.25 = (18.75 + 150 =) 170 (168.75) W [3]
6(b)(iii)[3]
IP = (15 / 12 =) 1.25 (A) and IQ = (15 / 1.5 =) 10 (A) vP / vQ = IPnAQe / IQnAPe or (1.25 × πd 2) / (10 × πd 2/4) = 0.5 [3]
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