JEE Main Physics — Modern Physics previous year questions with solutions.
The above is a plot of binding energy per nucleon $E_b$, against the nuclear mass $M ; A, B, C, D, E, F$ correspond to different nuclei. Consider four reactions: (i) $A+B \rightarrow C+\varepsilon$ (ii) $\mathrm{C} \rightarrow \mathrm{A}+\mathrm{B}+\varepsilon$ (iii) $\mathrm{D}+\mathrm{E} \rightarrow \mathrm{F}+\varepsilon$ and (iv) $F \rightarrow D+E+\varepsilon$ where $\varepsilon$ is the energy released? In which reactions is $\varepsilon$ positive? 
The logic circuit shown below has the input waveforms 'A' and 'B' as shown. Pick out the correct output waveform.  
A p-n junction (D) shown in the figure can act as a rectifier. An alternating current source $(V)$ is connected in the circuit. 
The transition from the state $n=4$ to $n=3$ in a hydrogen like atom results in ultraviolet radiation. Infrared radiation will be obtained in the transition from
The surface of a metal is illuminated with the light of $400 \mathrm{~nm}$. The kinetic energy of the ejected photoelectrons was found to be $1.68 \mathrm{eV}$. The work function of the metal is $(\mathrm{hc}=1240 \mathrm{eV} \mathrm{nm})$
In the circuit below, $A$ and $B$ represent two inputs and $C$ represents the output. The circuit represents 
Suppose an electron is attracted towards the origin by a force $k / r$ where ' $k$ ' is a constant and ' $r$ ' is the distance of the electron from the origin. By applying Bohr model to this system, the radius of the $n^{\text {th }}$ orbital of the electron is found to be ' $r_n$ ' and the kinetic energy of the electron to be $T_n$. Then which of the following is true?
This question contains Statement $-1$ and Statement-2. Of the four choices given after the statements, choose the one that best describes the two statements. Statement - I: Energy is released when heavy nuclei undergo fission or light nuclei undergo fusion. and Statement - II For heavy nuclei, binding energy per nucleon increases with increasing $Z$ while for light nuclei it decrease with increasing $Z$.
If $\mathrm{M_o}$ is the mass of an oxygen isotope $\mathrm{{ }_8 O^{17}, M_p}$ and $\mathrm{M_N}$ are the masses of a proton and a neutron respectively, the nuclear binding energy of the isotope is
Which of the following transitions in hydrogen atoms emit photons of highest frequency?
If in a $\mathrm{p-n}$ junction diode, a square input signal of $10 \mathrm{~V}$ is applied as shown   Then the output signal across $R_{\mathrm{L}}$ will be
Carbon, silicon and germanium have four valence electrons each. At room temperature which one of the following statements is most appropriate?
Photon of frequency $\mathrm{v}$ has a momentum associated with it. If $\mathrm{c}$ is the velocity of light, the momentum is
A solid which is transparent to visible light and whose conductivity increases with temperature is formed by
An alpha nucleus of energy $\frac{1}{2} m v^2$ bombards a heavy nuclear target of charge Ze. Then the distance of closest approach for the alpha nucleus will be proportional to
In the following, which one of the diodes is reverse biased?
The anode voltage of a photocell is kept fixed. The wavelength $\lambda$ of the light falling on the cathode is gradually changed. The plate current $\mathrm{I}$ of the photocell varies as follows :
If the lattice constant of this semiconductor is decreased, then which of the following is correct? 
If the binding energy per nucleon in ${ }_3^7 \mathrm{Li}$ and ${ }_2^4 \mathrm{He}$ nuclei are $5.60 \mathrm{MeV}$ and $7.06 \mathrm{MeV}$ respectively, then in the reaction $\mathrm{p}+{ }_3^7 \mathrm{Li} \rightarrow 2{ }_2^4 \mathrm{He}$ energy of proton must be
The threshold frequency for a metallic surface corresponds to an energy of $6.2 \mathrm{eV}$, and the stopping potential for a radiation incident on this surface $5 \mathrm{~V}$. The incident radiation lies in
When ${ }_3 \mathrm{Li}^{\prime}$ nuclei are bombarded by protons, and the resultant nuclei are ${ }_4 \mathrm{Be}^8$, the emitted particles will be
The circuit has two oppositely connect ideal diodes in parallel. What is the current following in the circuit? 
If the ratio of the concentration of electrons that of holes in a semiconductor is $\frac{7}{5}$ and the ratio of currents is $\frac{7}{4}$, then what is the ratio of their drift velocities?
The time by a photoelectron to come out after the photon strikes is approximately