Question 431: 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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