Question

A subatomic particle has a -1 relative unit charge and the ratio of charge to mass is $1.758820\times {10}^{11}Ck{g}^{–1}$. Find the absolute mass of the sub-atomic particle in kg.

• A. $6.4\times {10}^{-31}kg$
• B. $9.1\times {10}^{-31}kg$
• C. $9.1\times {10}^{-30}kg$
• D. $3.8\times {10}^{-31}kg$

Answer 1

The correct option is B $9.1\times {10}^{-31}kg$

$\frac{e}{m}=1.758820\times {10}^{11}Ck{g}^{–1}$

$-1$ relative charge is equal to $-1.601\times {10}^{-19}C$

$\frac{e}{e/m}=\frac{-1.601\times {10}^{-19}C}{1.758820\times {10}^{11}Ck{g}^{–1}}$

$\Rightarrow m=9.1\times {10}^{-31}kg$