Question

The energy of electron in first excited state of hydrogen atom is $-3.4\text{eV}$, its kinetic energy is,

• A. $-3.4\text{eV}$
• B. $+3.4\text{eV}$
• C. $-6.8\text{eV}$
• D. $+6.8\text{eV}$

Answer 1

The correct option is B $+3.4\text{eV}$

We know that,
$|K.E.|=|T.E.|=\frac{1}{2}|P.E|$

So, $K.E.=|\text{Total energy}|$
As, $T.E=-3.4\text{eV}$
$\Rightarrow$ $K.E=3.4\text{eV}$

Hence, $\left(B\right)$ is the correct answer.