JEE Main Physics — Modern Physics previous year questions with solutions.
Given below are two statements: Statement I: Most of the mass of the atom and all its positive charge are concentrated in a tiny nucleus and the electrons revolve around it, is Rutherford's model. Statement II: An atom is a spherical cloud of positive charges with electrons embedded in it, is a special case of Rutherford's model. In the light of the above statements, choose the most appropriate from the options given below.
When a hydrogen atom going from $n=2$ to $n=1$ emits a photon, its recoil speed is $\frac{x}{5}m{s}^{-1}$. Where $x=$_______. (Use: mass of hydrogen atom $=1.6\times {10}^{-27}\mathrm{kg}$, charge of electron $e=1.6\times {10}^{-19}C)$
The mass defect in a particular reaction is $0.4g$. The amount of energy liberated is $n\times {10}^{7}\mathrm{kW}h$, where $n=$ _____. (speed of light $=3\times {10}^{8}m{s}^{-1}$)
The output $\mathrm{Y}$ of following circuit for given inputs is : 
The de-Broglie wavelength of an electron is the same as that of a photon. If velocity of electron is $25%$ of the velocity of light, then the ratio of K.E. of electron and K.E. of photon will be:
In a nuclear fission reaction of an isotope of mass $M$, three similar daughter nuclei of same mass are formed. The speed of a daughter nuclei in terms of mass defect $\Delta M$ will be :
If $M_o$ is the mass of isotope ${ }_5^{12} B, M_P$ and $M_n$ are the masses of proton and neutron, then nuclear binding energy of isotope is :
In a photoelectric effect experiment a light of frequency $1.5$ times the threshold frequency is made to fall on the surface of photosensitive material. Now if the frequency is halved and intensity is doubled, the number of photo electrons emitted will be:
UV light of $4.13 \mathrm{eV}$ is incident on a photosensitive metal surface having work function $3.13 \mathrm{eV}$. The maximum kinetic energy of ejected photoelectrons will be:
A proton, an electron and an alpha particle have the same energies. Their de-Broglie wavelengths will be compared as :
The value of net resistance of the network as shown in the given figure is : 
The radius of a nucleus of mass number $64$ is $4.8$ fermi. Then the mass number of another nucleus having radius of $4$ fermi is $\frac{1000}{x},$ where $x$ is _________.
In photoelectric experiment energy of $2.48 \mathrm{eV}$ irradiates a photo sensitive material. The stopping potential was measured to be $0.5 \mathrm{~V}$. Work function of the photo sensitive material is :
A proton and an electron are associated with same de-Broglie wavelength. The ratio of their kinetic energies is: (Assume h=6.63 $\times 10^{-34} \mathrm{~J} \mathrm{~s}, \mathrm{~m}_{\mathrm{e}}=9.0 \times 10^{-31} \mathrm{~kg}$ and $\mathrm{m}_{\mathrm{p}}=1836$ times $\mathrm{m}_{\mathrm{e}}$ )
When UV light of wavelength $300 \mathrm{~nm}$ is incident on the metal surface having work function $2.13 \mathrm{eV}$, electron emission takes place. The stopping potential is: (Given hc $=1240 \mathrm{eV} \mathrm{nm}$ )
Which of the following phenomena does not explain by wave nature of light. A. reflection B. diffraction C. photoelectric effect D. interference E. polarization Choose the most appropriate answer from the options given below:
Given below are two statements :  Statement I : Figure shows the variation of stopping potential with frequency $(v)$ for the two photosensitive materials $\mathrm{M}_1$ and $\mathrm{M}_2$. The slope gives value of $\frac{\mathrm{h}}{\mathrm{e}}$, where $\mathrm{h}$ is Planck's constant, $\mathrm{e}$ is the charge of electron. Statement II : $\mathrm{M}_2$ will emit photoelectrons of greater kinetic energy for the incident radiation having same frequency. In the light of the above statements, choose the most appropriate answer from the options given below.
An electron rotates in a circle around a nucleus having positive charge Ze. Correct relation between total energy (E) of electron to its potential energy (U) is :
In Franck-Hertz experiment, the first dip in the current-voltage graph for hydrogen is observed at 10.2 V. The wavelength of light emitted by hydrogen atom when excited to the first excitation level is _________ $\mathrm{nm}$. (Given $\mathrm{hc}=1245 \mathrm{eV} \mathrm{nm}, \mathrm{e}=1.6 \times 10^{-19} \mathrm{C}$ ).
A star has $100 \%$ helium composition. It starts to convert three ${ }^4 \mathrm{He}$ into one ${ }^{12} \mathrm{C}$ via triple alpha process as ${ }^4 \mathrm{He}+{ }^4 \mathrm{He}+{ }^4 \mathrm{He} \rightarrow{ }^{12} \mathrm{C}+\mathrm{Q}$. The mass of the star is $2.0 \times 10^{32} \mathrm{~kg}$ and it generates energy at the rate of $5.808 \times 10^{30} \mathrm{~W}$. The rate of converting these ${ }^4 \mathrm{He}$ to ${ }^{12} \mathrm{C}$ is $\mathrm{n} \times 10^{42} \mathrm{~s}^{-1}$, where $\mathrm{n}$ is _________ [ Take, mass of ${ }^4 \mathrm{He}=4.0026 \mathrm{u}$, mass of ${ }^{12} \mathrm{C}=12 \mathrm{u}$ ]
A nucleus has mass number ${A}_{1}$ and volume ${V}_{1}$. Another nucleus has mass number ${A}_{2}$ and volume ${V}_{2}$. If relation between mass number is ${A}_{2}=4{A}_{1}$, then $\frac{{V}_{2}}{{V}_{1}}=$ _______.
The work function of a substance is $3.0\mathrm{eV}$. The longest wavelength of light that can cause the emission of photoelectrons from this substance is approximately:
In the given circuit, the voltage across load resistance $({R}_{L})$ is: 
The truth table for this given circuit is: 