Question

If the electron in a Hydrogen atom makes $6.25$$\times$ 10${}^{15}$ revolutions in one second, the current is:

• A. 1) 1.12 mA
• B. 2) 1 mA
• C. 3) 1.25 mA
• D. 4) 1.5 mA

Answer 1

The correct option is B 2) 1 mA

$\text{Step 1: Relation between Current, frequency and charge}$

Frequency of revolution, $f=6.25\times {10}^{15}$

A revolving electron can be assumed as equivalent current. We consider current in one time period, Therefore, the charge crossing in one time period is $e$.

From the definition of current,

$I=\frac{Q}{T}$

We know ,$f=1/T$

$\Rightarrow I=Q\times f$ $....\left(1\right)$

$\text{Step 2: Finding Current}$

Put the values in equation $\left(1\right)$

$I=Q\times f$

$=1.6\times {10}^{-19}C\times 6.25\times {10}^{15}$
$={10}^{-3}A=1mA$

Hence, Option B is correct