Question 354: Current Electricity

Question

The resistance of hot tungsten filament is about $$10$$ times the cold resistance. What will be resistance of $$100$$ $$W$$ and $$200$$ $$V$$ lamp when not in use ?

Accepted Answer

$$P = Vi = {{{V_2}} \over R}$$
$${R_{hot}} = {{{V^2}} \over P} = {{200 	imes 200} \over {100}} = 400\Omega $$
$${R_{cold}} = {{400} \over {10}} = 40\Omega $$

Answer

$$20\Omega $$

Answer

$$40\Omega $$

Answer

$$200\Omega $$

Answer

$$400\Omega $$

Current Electricity

The resistance of hot tungsten filament is about $10 times the cold resistance. What will be resistance of 100 W and 200 V$ lamp when not in use ?

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