The first line in the Lyman series has wavelength $\lambda $ . The wavlength of the first line in Balmer series is
$\frac{2}{9}\,\lambda $
$\frac{9}{2}\,\lambda $
$\frac{5}{27}\,\lambda $
$\frac{27}{5}\,\lambda $
An $X-$ ray tube is operated at $50\, kV$. the minimum wavelength produced is.......$\mathop A\limits^o $
In an alpha particle scattering experiment distance of closest approach for the $\alpha$ particle is $4.5 \times 10^{-14} \mathrm{~m}$. If target nucleus has atomic number $80$ , then maximum velocity of $\alpha$-particle is . . . . .. $\times 10^5$ $\mathrm{m} / \mathrm{s}$ approximately.
$\left(\frac{1}{4 \pi \epsilon_0}=9 \times 10^9 \mathrm{SI}\right.$ unit, mass of $\alpha$ particle $=$ $\left.6.72 \times 10^{-27} \mathrm{~kg}\right)$
The ratio of the speed of the electrons in the ground state of hydrogen to the speed of light in vacuum is
Explain the formulas of energy of electron in atom revolving around the nucleus in different orbits.
The radius of a nucleus is given by $r_0 A^{1 / 3}$, where $r_0=1.3 \times 10^{-15} \,m$ and $A$ is the mass number of the nucleus. The lead nucleus has $A=206$. The electrostatic force between two protons in this nucleus is approximately ................ $N$