Question 656: Current Electricity

Question

A filament bulb (500 W, 100 V) is to be used in a 230 V main supply. When a resistance R is connected in series, it works perfectly and the bulb consumes 500 W. The value of R is

Accepted Answer

Resistance of bulb,
$${R_B} = {{{V^2}} \over P} = {{{{\left( {100} ight)}^2}} \over {500}} = 20\Omega $$
Power of the bulb in the circuit,
P = VI
$$I = {P \over {{V_B}}}$$
$$ = {{500} \over {100}} = 5A$$
V
R
= IR  $$ \Rightarrow $$  (230 Ã¢ÂÂ 100) = 5 ÃÂ R
$$ 	herefore $$ R = 26 $$\Omega $$

Answer

230 $$\Omega $$

Answer

46 $$\Omega $$

Answer

26 $$\Omega $$

Answer

13 $$\Omega $$

Current Electricity

A filament bulb (500 W, 100 V) is to be used in a 230 V main supply. When a resistance R is connected in series, it works perfectly and the bulb consumes 500 W. The value of R is

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