Two radiations having energies $E_1$ and $E_2$ as $15 \ eV$ and $45 \ eV$ respectively,then the relationship between $\lambda_1$ and $\lambda_2$ will be:

Match the following:

List-$I$	List-$II$
$(1)$ $X$-rays	$(A)$ $\nu = 10^0 - 10^4 \ Hz$
$(2)$ Ultraviolet $(UV)$ rays	$(B)$ $\nu = 10^{10} \ Hz$
$(3)$ Long radio waves	$(C)$ $\nu = 10^{16} \ Hz$
$(4)$ Microwave	$(D)$ $\nu = 10^{18} \ Hz$

What is a black body?

Identify the correct statements from the following:
$I$) Isotopes of an element show different chemical behaviour
$II$) Lyman series of lines of hydrogen spectrum appear in $UV$ region
$III$) The oscillating electric and magnetic field components of electromagnetic radiation are perpendicular to each other and both are perpendicular to the direction of propagation of radiation

The ratio of the energy of a photon with wavelength $3000 \ \mathring{A}$ to that of a photon with wavelength $6000 \ \mathring{A}$ is:

If the energies of two photons are in the ratio of $3:2$,their wavelengths will be in the ratio of