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(D) The electric field $E$ inside the wire is given by $E = \frac{V}{l} = \frac{IR}{l}$,where $V$ is the potential difference across the wire.The magn

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$\frac{I^2R}{2\pi al}$

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(D) The electric field $E$ inside the wire is given by $E = \frac{V}{l} = \frac{IR}{l}$,where $V$ is the potential difference across the wire.The magnetic field $B$ at the surface of the wire is given by Ampere's Law as $B = \frac{\mu_0 I}{2\pi a}$,where $a$ is the radius of the wire.The Poynting vector $S$ is defined as $S = \frac{1}{\mu_0} (E 	imes B)$. Since $E$ is parallel to the wire and $B$ is tangential,the magnitude of the Poynting vector is $S = \frac{EB}{\mu_0}$.Substituting the values of $E$ and $B$:$S = \frac{1}{\mu_0} \left( \frac{IR}{l} ight) \left( \frac{\mu_0 I}{2\pi a} ight) = \frac{I^2R}{2\pi al}$.This vector is directed radially inward,representing the energy flow into the wire to account for Joule heating.

List-$I$	List-$II$
$(A)$ Gauss's law	$(I)$ Surface charge density
$(B)$ Faraday's law	$(II)$ Electric charge and energy conservation
$(C)$ Ampere's law	$(III)$ Change in magnetic flux
$(D)$ Kirchhoff's law	$(IV)$ Change in electric flux
	$(V)$ Total electric flux

$A$ long straight wire of resistance $R$,radius $a$,and length $l$ carries a constant current $I$. The Poynting vector for the wire will be

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