Arrange the following types of radiation in increasing order of frequency:
$(a)$ radiation from microwave oven
$(b)$ amber light from traffic signal
$(c)$ radiation from $FM$ radio
$(d)$ cosmic rays from outer space
$(e)$ $X$-rays

$A$ photon-sensitive metal is not emitting photoelectrons when irradiated. It will do so when the threshold is crossed. To cross the threshold,we need to increase:

The work functions of $Ag, Mg, K$ and $Na$ respectively in $eV$ are $4.3, 3.7, 2.25, 2.30$. When an electromagnetic radiation of wavelength of $300 \ nm$ is allowed to fall on these metal surfaces,the number of metals from which the electrons are ejected is $(eV = 1.6022 \times 10^{-19} \ J)$

Explain line spectra and its uses.

Find the energy of radiation having $7000 \ \mathring{A}$ and $400 \ nm$ wavelength. $\left( h = 6.62 \times 10^{-34} \ J \ s, c = 3 \times 10^8 \ m/s \right)$

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