Question 348: Current Electricity

Question

The resistance of bulb filmanet is $$100\Omega $$ at a temperature of $${100^ \circ }C.$$ If its temperature coefficient of resistance be $$0.005$$ per $$^ \circ C$$, its resistance will become $$200\,\Omega $$ at a temperature of

Accepted Answer

$$R{}_1 = {R_0}\left[ {1 + \alpha  	imes 100} ight] = 100\,\,\,\,\,\,\,\,\,\,\,...\left( 1 ight)$$
$${R_2} = {R_0}\left[ {1 + \alpha  	imes T} ight] = 200\,\,\,\,\,\,\,\,\,\,\,\,\,\,...\left( 2 ight)$$
On dividing we get
$${{200} \over {100}} = {{1 + \alpha T} \over {1 + 100\alpha }}$$
$$ \Rightarrow 2 = {{1 + 0.005T} \over {1 + 100 	imes 0.005}}$$
$$ \Rightarrow T = {400^ \circ }C$$
NOTE :
We may use this expression as an approximation because the difference in the answers is appreciable. For accurate results one should use $$R = {R_0}{e^{\alpha \Delta T}}$$

Answer

$${300^ \circ }C$$

Answer

$${400^ \circ }C$$

Answer

$${500^ \circ }C$$

Answer

$${200^ \circ }C$$

Current Electricity

The resistance of bulb filmanet is $100\Omega at a temperature of {100^ \circ }C. If its temperature coefficient of resistance be 0.005 per ^ \circ C, its resistance will become 200\,\Omega $ at a temperature of

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