Question

A body has $80$ micro-coulomb of negative charge. Number of electrons on it will be :

• A. $8\times {10}^{-5}$
• B. $80\times {10}^{15}$
• C. $5\times {10}^{14}$
• D. $1.28\times {10}^{-17}$

Answer 1

The correct option is C $5\times {10}^{14}$

$\text{Step 1: Quantization of charge}$

We know that from the property of quantization of charge, charge on the body can be given by: $Q=ne$

No. of electrons $\left(n\right)=\frac{\text{Total charge on the body (Q)}}{\text{Charge on an electron (e)}}$

$=\frac{80\times {10}^{-6}C}{1.6\times {10}^{-19}C}$$=5\times {10}^{14}$ electrons

Hence, option C is correct.