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Q.
The number of electrons moving per second through the filament of a lamp of $100 \,W$, operating at $200\, V$ is
Current Electricity
Solution:
$P=V i \Rightarrow i=\frac{P}{V}=\frac{100}{200}=0.5 A$
Charge passing through the lamp in $1 s$
$q=i \times t=0.5 \times 1=0.5 C (\because t=1 s )$
Therefore, number of electrons moving through the filament per second
$N=q / e=\frac{0.5}{1.6 \times 10^{-19}}=3.125 \times 10^{18}$