Two bulbs are rated as 80 W, 220 V and 120 W, 220 V respectively. The ratio of…
2024
Two bulbs are rated as 80 W, 220 V and 120 W, 220 V respectively. The ratio of their resistances is:
- A.
2:1
- B.
3:2
- C.
2:3
- D.
1:2
- E.
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Correct answer: B
The resistance of a bulb is calculated using the formula R = V²/P. Since both bulbs operate at the same voltage of 220 V, resistance is inversely proportional to power. The ratio of resistances R₁:R₂ equals the inverse ratio of their powers, which is 120:80. Simplifying this fraction gives 3:2.