JEE Main · 2026 · 22 Jan 2026 · Shift 2 · Modern Physics

7.9 MeV α-particle scatters from a target material of atomic number 79. From the given data the estimated diameter of nuclei of the target material is (approximately) ______ m.
[$\frac{1}{4\pi {ϵ}_0}=9\times 10^9$ Nm²/C² and electron charge $=1.6\times 10^{-19}$ C]

The minimum frequency of photon required to break a particle of mass 15.348 amu into $4\alpha$ particles is ______ kHz.
[mass of He nucleus = 4.002 amu, $1$ amu $=1.66\times 10^{-27}$ kg, $h=6.6\times 10^{-34}$ J.s and $c=3\times 10^8$ m/s]

The smallest wavelength of Lyman series is 91 nm. The difference between the largest wavelengths of Paschen and Balmer series is nearly $\_\_\_\_$ nm.

The energy of an electron in an orbit of the Bohr's atom is $-0.04{\mathrm{E}}_0\mathrm{eV}$ where ${\mathrm{E}}_0$ is the ground state energy. If L is the angular momentum of the electron in this orbit and h is the Planck's constant, then …

A particle having electric charge $3\times 10^{-19}\mathrm{C}$ and mass $6\times 10^{-27}\mathrm{kg}$ is accelerated by applying an electric potential of 1.21 V . Wavelength of the matter wave associated with the particle is $\alpha \times 10^{-12}\mathrm{m}$. The va …

The de Broglie wavelength of an oxygen molecule at $27^{\circ }\text{C}$ is $x\times 10^{-12}\text{ m}$. The value of x is (take Planck's constant $=6.63\times 10^{-34}\text{ J⋅s}$, Boltzmann constant $=1.38\times 10^{-23}\text{ J/K}$, mass of oxygen molecule …