In India, electricity is supplied at 220 V whereas it is supplied at 110 V in USA. If the resistance of a 60 W bulb for use in India is R, its resistance for 60 W use in USA will be:
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In India, electricity is supplied at 220 V whereas it is supplied at 110 V in USA. If the resistance of a 60 W bulb for use in India is R, its resistance for 60 W use in USA will be:

G1 Physics · Accepted Answer

Step 1: For equal rated power, bulb R = V²/P. Step 2: Rᵤₛ/Rᵢₙ = (110/220)² = 1/4. Step 3: Rᵤₛ = R/4.