$\alpha$-rays have

Linear spectrum (line spectrum) is a characteristic of which of the following?

Explain the production,characteristics,and uses of $X$-rays.

$A$ hypothetical electromagnetic wave is shown below. The frequency of the wave is $x \times 10^{19} \ Hz$. $x =$ . . . . (nearest integer)

Electrons are emitted with zero velocity from a metal surface when it is exposed to radiation of wavelength $8000 \ \mathring{A}$. What should be the maximum velocity of emitted electron when the same metal surface is exposed to radiation of wavelength $5000 \ \mathring{A}$? $\left( h = 6.6 \times 10^{-34} \ J \cdot s, \ m_e = 9.1 \times 10^{-31} \ kg, \ c = 3 \times 10^8 \ m/s \right)$

Splitting of spectral lines under the influence of a magnetic field is called: