Question

How
many electrons pass through a wire in 2 minutes if current passing through the wire is
300 mA?​

Answer 1

Number of electrons = 2.25 × 10²⁰ electrons

Given :-

$\sf{Current \: (I) = 300 \: mA = 300\times 10^{-3} \: A}$

$\sf{Time \: (t) = 2 \: minutes = 120 \: seconds}$

To Find :-

$\sf{How \: many \: electrons \: pass \: through \: the \: wire \: ?}$

Using Formula :-

$\sf{Charge = Current\times Time}$

$\sf{Charge=no. \: of \: electrons\times charge \: on \: electron}$

Solution :-

$\sf{Q = It}$

$\sf{Q = 300\times 10^{-3}\times 120}$

$\sf{Q = 300\times 120\times 10^{-3}}$

$\sf{Q = 3000\times 12\times 10^{-3}}$

$\sf{Q = 3\times 10^{3}\times 10^{-3}\times 12}$

$\sf{Q = 3\times 12}$

$\sf{Q = 36 \: Coloumb}$

Now ,

$\sf{Q = ne}$

$\sf{36 = n\times (1.6\times 10^{-19})}$

$\sf{36 = n\times 16\times 10^{-20}}$

$\sf{36 = 16n\times 10^{-20}}$

$\sf{9 = 4n\times 10^{-20}}$

$\sf{4n = 9\times 10^{20}}$

$\sf{n = 2.25\times 10^{20} \: electrons}$