Question

A hypothetical sub-atomic particle has a mass $\frac{4}{9.1}$ times of an electron and a charge equal to that of a proton. Calculate the charge to mass ratio.

• A. $0.4\times {10}^{12}{\text{C kg}}^{-1}$
• B. $1.2\times {10}^{12}{\text{C kg}}^{-1}$
• C. $0.8\times {10}^{10}{\text{C kg}}^{-1}$
• D. $0.4\times {10}^{10}{\text{C kg}}^{-1}$

Answer 1

The correct option is A $0.4\times {10}^{12}{\text{C kg}}^{-1}$

Given,
$\text{Mass of the particle}=\frac{4\times \text{mass of electron}\left(m_e\right)}{9.1}=\frac{4m_e}{9.1}$

$\text{Charge of the particle}=+e$

$\therefore \text{Charge to mass ratio}=\frac{e}{\frac{4m_e}{9.1}}=\frac{9.1\times 1.6\times {10}^{-19}\text{C}}{4\times 9.1\times {10}^{-31}\text{kg}}=0.4\times {10}^{12}{\text{C kg}}^{-1}$