Question

Charge on a proton is $1.6\times {10}^{-19}\text{C}$ and its mass is calculated to be equal to $1.67\times {10}^{-27}\text{kg}$. Then $e/m$ for proton is:
($e:\text{Charge};m:\text{Mass}$)

• A. Less than $e/m$ value for electron
• B. Equal to $e/m$ value for electron
• C. Greater than $e/m$ value for electron
• D. Equal to $e/m$ value for neutron

Answer 1

The correct option is A Less than $e/m$ value for electron

Charge on proton $=1.6\times {10}^{-19}\text{C}$
Mass of proton $=1.67\times {10}^{-27}\text{kg}$
Value of $\frac{e}{m}=\frac{\text{Magnitude of charge on}proton}{\text{Mass of proton}}$

$=\frac{1.6\times {10}^{-19}\text{C}}{1.67\times {10}^{-27}\text{kg}}$

$=0.958\times {10}^8\text{C/kg}$
But $e/m$ value of electron is $1.75\times {10}^{11}\text{C/kg}$ which is greater than that of proton.