Question

When a piece of polythene is rubbed with wool, a charge of $-2\times {10}^{-7}C$ is developed on polythene. What mass is transferred to polythene?

• A. $5.69\times {10}^{-19}kg$
• B. $2.25\times {10}^{-19}kg$
• C. $9.63\times {10}^{-19}kg$
• D. $11.38\times {10}^{-19}kg$

Answer 1

Answer: (D)

$11.38\times {10}^{-19}kg$

As negative charge is developed on polythene, thus electrons get transferred from wool to the polythene.

Mass of one electron $m_e=9.1\times {10}^{-31}$ $kg$

Charge of one electron $q=1.6\times {10}^{-19}C$

$\therefore$ Mass of $2\times {10}^{-7}C$ charge, $M=\frac{m_e}{q}\times 2\times {10}^{-7}$ kg

$\therefore$ $M=\frac{9.1\times {10}^{-31}}{1.6\times {10}^{-19}}\times 2\times {10}^{-7}=11.38\times {10}^{-19}$ $kg$