JEE Main Physics — Modern Physics previous year questions with solutions.
A $H{e}^{+}$ ion is in its first excited state. Its ionization energy is:
The reverse break down voltage of a Zener diode is $5.6 V$ in the given circuit.  The current ${I}_{z}$ through the Zener is:
The logic gate equivalent to the given logic circuit is: 
A metal plate of area $1\times {10}^{-4}{m}^{2}$ is illuminated by a radiation of intensity $16\frac{milliW}{{m}^{2}}$ . The work function of the metal is $5eV.$ The energy of the incident photons is $10eV$ and only $10%$ of it produces photo electrons. The number of emitted photo electron per second and their maximum energy, respectively, will be: $[1 eV=1.6\times {10}^{-19}J]$
The de-Broglie wavelength $({\lambda }_{B})$ associated with the electron orbiting in the second excited state of hydrogen atom is related to that in the ground state $({\lambda }_{G})$ by:
Two electrons are moving with non-relativistic speeds perpendicular to each other. If corresponding de Broglie wavelengths are $\lambda_1$ and $\lambda_2$, their de Broglie wavelength in the frame of reference attached to their centre of mass is:
An electron from various excited states of hydrogen atom emit radiation to come to the ground state. Let ${\lambda }_{n}, {\lambda }_{g}$ be the de Broglie wavelength of the electron in the ${n}^{th}$ state and the ground state respectively. Let ${\wedge }_{n}$ be the wavelength of the emitted photon in the transition from the ${n}^{th}$ state to the ground state. For large n, (A, B are constants)
If the series limit frequency of the Lyman series is ${V}_{L},$ then the series limit frequency of the Pfund series is:
Both the nucleus and the atom of some element are in their respective first excited states. They get de-excited by emitting photons of wavelengths ${\lambda }_{N}, {\lambda }_{A}$ respectively. The ratio $\frac{{\lambda }_{N}}{{\lambda }_{A}}$ is closest to:
An unstable heavy nucleus at rest breaks into two nuclei which move away with velocities in the ratio of $8: 27$. The ratio of the radii of the nuclei (assumed to be spherical ) is:
The reading of the ammeter for a silicon diode in the given circuit is: 
Muon $\left(\mu^{-1}\right)$ is negatively charged $(|\mathrm{q}|=|\mathrm{e}|)$ with a mass $\mathrm{m}_\mu=200 \mathrm{~m}_{\mathrm{e}}$, where $\mathrm{m}_{\mathrm{e}}$ is the mass of the electron and e is the electronic charge. If $\mu^{-1}$ is bound to a proton to form a hydrogen like atom, identify the correct statements (A) Radius of the muonic orbit is 200 times smaller than that of the electron (B) the speed of the $\mu^{-1}$ in the $n$th orbit is $\frac{1}{200}$ times that of the election in the nth orbit (C) The lonization energy of muonic atom is 200 times more than that of an hydrogen atom (D) The momentum of the muon in the nth orbit is 200 times more than that of the electron
The energy required to remove the electron from a singly ionized Helium atom is $2.2$ times the energy required to remove an electron from helium atom. The total energy required to ionize the Helium atom completely is close to
In the given circuit the current through zener diode is: 
Truth table for the given circuit will be 
The energy required to remove the electron from a singly ionized Helium atom is $2.2$ times the energy required to remove an electron from Helium atom. The total energy required to ionize the Helium atom completely is:
If the de Broglie wavelengths associated with a proton and an $\alpha$-particle are equal, then the ratio of velocities of the proton and the $\alpha$-particle will be:
Two electrons are moving with non-relativistic speeds perpendicular to each other. If corresponding de brogile wavelengths are ${\lambda }_{1}$ and ${\lambda }_{2}$, their de brogile wavelength in the frame of reference attached to their centre of mass is:
A particle $A$ of mass $m$ and initial velocity $v$ collides with a particle $B$ of mass $\frac{m}{2}$ which is at rest. The collision is head on, and elastic. The ratio of the de-Broglie wavelengths ${\lambda }_{A}$ to ${\lambda }_{B}$ after the collision is:
The maximum velocity of the photoelectrons emitted from the surface is $v$ when light of frequency $n$ falls on a metal surface. If the incident frequency is increased to $3n$, the maximum velocity of the ejected photoelectrons will be:
Some energy levels of a molecule are shown in the figure. The ratio of the wavelengths $r=\frac{{\lambda }_{1}}{{\lambda }_{2}}$, is given by: 
A laser light of wavelength $660 \mathrm{nm}$ is used to weld Retina detachment. If a laser pulse of width $60 \mathrm{ms}$ and power $0.5\mathrm{kW}$ is used, the approximate number of photons in the pulse are (Take Planck's Constant, $h=6.62\times {10}^{-34} Js)$
The acceleration of an electron in the first orbit of the hydrogen atom ($n=1$) is :
Imagine that a reactor converts all the given mass into energy and that it operates at a power level of ${10}^{9}\mathrm{Watt}$ . The mass of the fuel consumed $\mathrm{per}\mathrm{hour}$, in the reactor, will be: (velocity of light, $c$ is $3\times {10}^{8 }m{s}^{-1}$)