# How many electrons flow through the filament of a $120V, 60W$ bulb in one second?

$\begin {array} {1 1} (A)\;3.125 \times 10^{18} & \quad (B)\;31.25 \times 10^{18} \\ (C)\;0.3125 \times 10^{18} & \quad (D)\;312.5 \times 10^{18} \end {array}$

$I = \large\frac{power}{voltage} =$ $0.5A$
No. of electrons per unit time equals current per unit charge
$\Rightarrow n = \large\frac{i.t}{e}$
e is the charge on the electron
Ans : (A)

edited Sep 10, 2014