Question
A current of 4 A flows through an automobile headlight. How many electrons flow through the headlight in a time of 2 hrs?

Answer

Given: $I =4 A , t =2$ hrs $=2 \times 60 \times 60 s$
To find: Number of electrons (N)
Formula: $I =\frac{q}{t}=\frac{N e}{t}$
Calculation: As we know, e $=1.6 \times 10^{-19} C$
From formula,
$
N =\frac{I t}{e}=\frac{4 \times 2 \times 60 \times 60}{1.6 \times 10^{-19}}=18 \times 10^{-23}
$

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