Question

Assertion $\left(A\right)-$ A current flows in a conductor only when there is an electric field within the conductor.
Reason $\left(R\right)-$ The drift velocity of electron in presence of electric field decreases

Of the following mark the correct statement.

• A. Both ${}^{\prime }{A}^{\prime }$ and ${}^{\prime }{R}^{\prime }$ are true and ${}^{\prime }{R}^{\prime }$ is the correct explanation of ${}^{\prime }{A}^{\prime }$.
• B. Both ${}^{\prime }{A}^{\prime }$ and ${}^{\prime }{R}^{\prime }$ are true and ${}^{\prime }{R}^{\prime }$ is not the correct explanation of ${}^{\prime }{A}^{\prime }$
• C. ${}^{\prime }{A}^{\prime }$ is true and ${}^{\prime }{R}^{\prime }$ is false
• D. ${}^{\prime }{A}^{\prime }$ is false and ${}^{\prime }{R}^{\prime }$ is true

Answer 1

The correct option is C ${}^{\prime }{A}^{\prime }$ is true and ${}^{\prime }{R}^{\prime }$ is false

The expression for drift velocity
$V_d=\frac{\sigma E}{ne}$
$e$ - change of the $e^{-}$
$E$ - electric field
$n$ - electron density
$\sigma$ - conductivity

As $V_d\propto E,$ Drift velocity increases with increase of electric field.