Question 705: Current Electricity

Question

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

Accepted Answer

$$P = {{{V^2}} \over R}$$
$$ \Rightarrow R = {{{V^2}} \over P} = {{{{\left( {220} ight)}^2}} \over {60}} = {{4 	imes {{\left( {110} ight)}^2}} \over {60}}$$
$$R' = {{{{\left( {110} ight)}^2}} \over {60}} = {R \over 4}$$

Answer

R

Answer

2R

Answer

R/4

Answer

R/2

Current Electricity

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

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