Question

The specific charge of a proton is $9.6\times {10}^7$ coulomb/Kg. Then the specific charge of an alpha particle is

• A. $2.4\times {10}^{7}C/kg$
• B. $4.8\times {10}^{7}C/kg$
• C. $9.6\times {10}^{7}C/kg$
• D. $1.4\times {10}^{7}C/kg$

Answer 1

Answer: (B)

$4.8\times {10}^{7}C/kg$

Specific charge $=\frac{q}{m}=>\frac{q_p}{m_p}=9.6\times {10}^7\frac{e}{kg}$
$\alpha$ - particle has charge twice of proton and mass 4 times of proton.
So, specific charge of $\alpha$-particle $=\frac{2q_p}{4m_p}$
$=\frac{1}{2}\left(\frac{q_p}{m_q}\right)$
$=\frac{1}{2}(9.6\times {10}^7)$
$=4.8\times {10}^7\frac{c}{kg}$