# A potential difference V is applied across a conductor of length L and diameter D. How is the drift velocity, vd, of charge carriers in the conductor affected when (i) V is halved, (ii) L is doubled - Physics

Short Note

A potential difference V is applied across a conductor of length L and diameter D. How is the drift velocity, vd, of charge carriers in the conductor affected when (i) V is halved, (ii) L is doubled and (iii) D is halved ? justify your answer in each case.

#### Solution

We know drift velocity is given by

|"V"_"d"| = "eτ"/"m" "E"

Also "E" = "V"/"L"

So |"v"_"d"| = "eτ"/"m"("V"/"L")

(i) When V is halved drift velocity (vd) gets halved

(ii) When L is doubled drift velocity (vd) gets halved

(iii) When D is halved drift velocity (vd) remains same.

Concept: Motion in Combined Electric and Magnetic Fields - Velocity Selector
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