Question

A current of $5A$ exists in a $10\Omega$ resistance for $4$ minutes. The number of electrons and charge in coulombs passing through any section of the resistor in this time are:

• A. $75\times {10}^{20}$, 600 C
• B. $75\times {10}^{21}$, 600 C
• C. $75\times {10}^{20}$, 1200 C
• D. $75\times {10}^{19}$, 1200 C

Answer 1

Answer: (C)

$75\times {10}^{20}$, 1200 C

Current , $i=\frac{Q}{t}$

or charge $Q=it=5\times (4\times 60)=1200C$

Number of electrons $n=\frac{Q}{e}=\frac{1200}{1.6\times {10}^{-19}}=75\times {10}^{20}$