Question

As a cat rubs its back along a carpet, it acquires a charge of $+8.2\times {10}^{-7}C$. How many electrons did it lose to the carpet?

• A. $5.12\times {10}^{19}$
• B. $5.12\times {10}^{12}$
• C. $51.2\times {10}^{12}$
• D. cannot be determined

Answer 1

The correct option is B

$5.12\times {10}^{12}$

It's given that charge acquired is $+8.2\times {10}^{-7}C$. Let’s say n electrons were lost to acquire the charge.

Now, charge on each electron is $–e=(–1.6\times {10}^{-19}C)$

So, ne = $8.2\times {10}^{-7}C$

$n=\frac{8.2\times {10}^{-7}C}{1.6\times {10}^{-19}}=5.12\times {10}^{12}$