What is impact parameter ?
The first line in the Lyman series has wavelength $\lambda $ . The wavlength of the first line in Balmer series is
In Rutherford's experiment, number of particles scattered at $90^{\circ}$ angle are $x$ per second. Number particles scattered per second at angle $60^{\circ}$ is
An $X-$ ray tube is operated at $50\, kV$. the minimum wavelength produced is.......$\mathop A\limits^o $
Ratio of longest wave lengths corresponding to Lyman and Balmer series in hydrogen spectrum is