Question 607: Current Electricity

Question

A copper wire of length 10 m and radius $$\left( {{{{{10}^{ - 2}}} \over {\sqrt \pi  }}} \right)$$ m has electrical resistance of 10 $$\Omega$$. The current density in the wire for an electric field strength of 10 (V/m) is

Accepted Answer

Resistance, $$R = ho {L \over A} = {L \over {\sigma A}}$$
$$ \Rightarrow \sigma  = {L \over {RA}}$$
Also current density $$j = \sigma E = {{LE} \over {RA}}$$
$$J = {{10 	imes 10} \over {10 	imes \pi {{\left( {{{{{10}^{ - 2}}} \over {\sqrt \pi  }}} ight)}^2}}} = {{100} \over {10 	imes \pi  	imes \left( {{{{{10}^{ - 4}}} \over \pi }} ight)}}$$
$$ = {10^5}$$ A/m
2

Answer

10
4
A/m
2

Answer

10
6
A/m
2

Answer

10
$$-$$5
A/m
2

Answer

10
5
A/m
2

Current Electricity

A copper wire of length 10 m and radius $\left( {{{{{10}^{ - 2}}} \over {\sqrt \pi }}} \right) m has electrical resistance of 10 \Omega$. The current density in the wire for an electric field strength of 10 (V/m) is

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