Question

Two copper wires having their radii in the ratio of \(3:2\) are connected in series across a battery. Find the ratio of the drift velocities of the electrons in the wires.

Hint:

For wires connected in series: \[ I_1 = I_2 \] Using \[ I = neAv_d \] we get \[ v_d \propto \frac{1}{A} \] and since \[ A=\pi r^2, \] \[ v_d \propto \frac{1}{r^2} \] Therefore, drift velocity is inversely proportional to the square of the radius of the wire.

Answer 1