Question

The ratio of specific charge $e/m$ of an electron to that of a hydrogen ion is

• A. $1:1$
• B. $1840:1$
• C. $1:1840$
• D. $2:1$

Answer 1

The correct option is B $1840:1$

Specific charge of electron, $a=\frac{e}{m}=\frac{1.66\times {10}^{-19}}{9.1\times {10}^{-31}}=1.76\times {10}^{11}$

Specific charge of hydrogen, $a_1=\frac{e}{m}=\frac{1.66\times {10}^{-19}}{1.68\times {10}^{-27}}=9.58\times {10}^7$

$\Rightarrow \frac{a_1}{a_2}=1840$