The ratio of the speed of the electrons in the ground state of hydrogen to the speed of light in vacuum is
$1 / 2$
$2 / 137$
$1 / 137$
$1 / 237$
Ratio of longest wavelengths corresponding to Lyman and Balmer series in hydrogen spectrum is
What was the thickness of the gold foil kept in the Geiger-Marsden scattering experiment?
In the following diagram, which particle has highest $e/m$ value?
$\sqrt{d_{1}}$ and $\sqrt{d_{2}}$ are the impact parameters corresponding to scattering angles $60^{\circ}$ and $90^{\circ}$ respectively, when an $\alpha$ particle is approaching a gold nucleus. For $d_{1}=x d_{2}$, the value of $x$ will be ________
An alpha nucleus of energy $\frac{1}{2}mv^2$ bombards a heavy nuclear target of charge $Ze.$ Then the distance of closest approach for the alpha nucleus will be proportional to