- Consider a conductor with cross-sectional area A. Assume that the two ends of the conductor are connected to a battery to make the current flow through it.
- Let ‘${{V}_{d}}$’ be the drift speed of the charges and ‘n’ be the number of charges present in the conductor in an unit volume.
- The distance covered by each charge in one second is ‘${{V}_{d}}$’.
- Then the volume of the conductor for this distance = $A{{V}_{d}}$
- The number of charges contained in that volume = n.$A{{V}_{d}}$
- Let q be the charge of each carrier.
- Then the total charges crossing the cross-sectional area at position D in one second is 'nq $A{{V}
*{d}}$’.*{d}}$.

This is equal to electric current.

.-. Electric current I = nq $A{{V}

Therefore , ${{V}_{d}}$ = 1/nqA

# Derive an expression to find drift velocity of electrons

**prasanna**#1