Question

76. Bulb 'P' marked as 100 W, 220 V and bulb Q
marked as 60 W, 110 V. The resistance ratio of
P and Q is
(1) 12:7
(2) 5:7
(3) 5:12
(4) 12:5​

Answer 1

answer : option (4) 12 : 5

resistance of Bulb P : given, power = 100W and voltage = 220V

Resistance of bulb P = (voltage)²/power

= (220V)²/100W

= 484 Ω

resistance of Bulb Q : given, power = 60W and voltage = 110V

so, resistance of bulb Q = (voltage)/²/power

= (110)²/60

= 605/3 Ω

now ratio of resistance of bulb P : resistance of bulb Q = 484 : 605/3

= 484 × 3 : 605

= 121 × 4 × 3 : 121 × 5

= 12 : 5

hence, option (4) is correct choice.

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Answer 2

$\huge\bold\purple{Answer:-}$

4) 12:5