Question

e/m value of an electron is:

• A. $1.76\times {10}^8\text{C/kg}$
• B. $1.76\times {10}^{11}\text{C/kg}$
• C. $1.6\times {10}^{19}\text{C/kg}$
• D. $4.8\times {10}^{10}\text{C/kg}$

Answer 1

The correct option is B $1.76\times {10}^{11}\text{C/kg}$

Charge on an electron is $1.6\times {10}^{-19}\text{C}$ and mass of electron is $9.1\times {10}^{-31}\text{kg}$.
$\therefore \frac{e}{m}=\frac{1.6\times {10}^{-19}\text{C}}{9.1\times {10}^{-31}\text{kg}}=1.76\times {10}^{11}\text{C/kg}$