The potential energy of the orbital electron in the ground state of hydrogen atoms is $-\mathrm{E}$. What is…

The potential energy of the orbital electron in the ground state of hydrogen atoms is $-\mathrm{E}$. What is the kinetic energy?
  1. $4 \mathrm{E}$
  2. $\frac{E}{4}$
  3. $\frac{E}{2}$
  4. $2 E$

Solution

The potential energy of $\mathrm{U}(\mathrm{n}=1)=-\mathrm{E}$ Ground state: total energy is given by $\mathrm{TE}=\mathrm{U}+\mathrm{K}$ $\mathrm{U}=-\frac{\left(\mathrm{ze}^2\right)}{4 \pi \varepsilon_0}$ For orbit consider force balance $\frac{\mathrm{ze}^2}{4 \pi \varepsilon_0 \mathrm{r}^2}=\frac{\mathrm{mv}^2}{\mathrm{r}}$ $\therefore \mathrm{K}=\frac{\mathrm{mv}^2}{2}=\frac{1}{2}\left(\frac{\mathrm{ze}^2}{4 \pi \varepsilon_0 \mathrm{r}^2}\right)$ Thus, $\mathrm{K}=\frac{\mathrm{E}}{2}=\frac{\mathrm{U}}{2}$

Asked in: MHT CET 2022 (08 Aug Shift 2)

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