Modern Physics PYQ — Page 5

Match the LIST-I with LIST-II $\begin{array}{|l|l|l|l|}\hline & \text{LIST-I} & & \text{LIST-II} \\ \hline \text{A.} & \begin{array}{l} { }_0^1 \mathrm{n}+{ }_{92}^{235} \mathrm{U} \\ \rightarrow{ }_{54}^{140} \mathrm{Xe}+{ }_{38}^{94} \mathrm{Sr}+2{ }_0^1 \mathrm{n} \end{array} & \text{I.} & \begin{array}{l} \text{Chemical} \\ \text{reaction} \end{array} \\ \hline \text{B.} & 2 \mathrm{H}_2+\mathrm{O}_2 \rightarrow 2 \mathrm{H}_2 \mathrm{O} & \text{II.} & \begin{array}{l} \text{Fusion} \\ \text{with +ve} \\ \text{Q value} \end{array} \\ \hline \text{C.} & { }_1^2 \mathrm{H}+{ }_1^2 \mathrm{H} \rightarrow{ }_2^3 \mathrm{He}+{ }_0^1 \mathrm{n} & \text{III.} & \text{Fission} \\ \hline \text{D.} & { }_1^1 \mathrm{H}+{ }_1^3 \mathrm{H} \rightarrow{ }_1^2 \mathrm{H}+{ }_1^2 \mathrm{H} & \text{IV.} & \begin{array}{l} \text{Fusion} \\ \text{with -ve Q} \\ \text{value} \end{array} \\ \hline\end{array}$ Choose the correct answer from the options given below :

The output voltage in the following circuit is (Consider ideal diode case) 

In a hydrogen like ion, the energy difference between the $2^{\text {nd }}$ excitation energy state and ground is 108.8 eV. The atomic number of the ion is

Assuming the validity of Bohr's atomic model for hydrogen like ions the radius of $\mathrm{Li}^{++}$ion in its ground state is given by $\frac{1}{X} a_0$, where $X=$ _______. (Where $\mathrm{a}_0$ is the first Bohr's radius.)

 In the circuit shown here, assuming threshold voltage of diode is negligibly small, then voltage $V_{A B}$ is correctly represented by :

The work functions of cesium (Cs) and lithium (Li) metals are 1.9 eV and 2.5 eV , respectively. If we incident a light of wavelength 550 nm on these two metal surfaces, then photo-electric effect is possible for the case of

For a hydrogen atom, the ratio of the largest wavelength of Lyman series to that of the Balmer series is.

 \begin{array}{c|c|c} A & B & Y \\\hline 0 & 0 & 1 \\0 & 1 & 1 \\1 & 0 & 0 \\1 & 1 & 1\end{array} To obtain the given truth table, following logic gate should be placed at G:

The work function of a metal is 3 eV. The color of the visible light that is required to cause emission of photoelectrons is

A small mirror of mass $m$ is suspended by a massless thread of length $l$. Then the small angle through which the thread will be deflected when a short pulse of laser of energy $E$ falls normal on the mirror ( $\mathrm{c}=$ speed of light in vacuum and $\mathrm{g}=$ acceleration due to gravity)

In the digital circuit shown in the figure, for the given inputs the P and Q values are : 

The number of spectral lines emitted by atomic hydrogen that is in the $4^{\text {th }}$ energy level, is

A sub-atomic particle of mass $10^{-30} \mathrm{~kg}$ is moving with a velocity $2.21 \times 10^6 \mathrm{~m} / \mathrm{s}$. Under the matter wave consideration, the particle will behave closely like $\qquad$ $\left(\mathrm{h}=6.63 \times 10^{-34} \mathrm{~J} . \mathrm{s}\right)$

The truth table corresponding to the circuit given below is 

A radioactive nucleus $n_2$ has 3 times the decay constant as compared to the decay constant of another radioactive nucleus $n_1$. If initial number of both nuclei are the same, what is the ratio of number of nuclei of $n_2$ to the number of nuclei of $n_1$, after one half-life of $n_1$ ?

An electron in the hydrogen atom initially in the fourth excited state makes a transition to $\mathrm{n}^{\text {th }}$ energy state by emitting a photon of energy 2.86 eV. The integer value of $n$ will be ____.

Arrange the following in the ascending order of wavelength $(\lambda)$ : (A) Microwaves $\left(\lambda_1\right)$ (B) Ultraviolet rays $\left(\lambda_2\right)$ (C) Infrared rays $\left(\lambda_3\right)$ (D) X-rays $\left(\lambda_4\right)$ Choose the most appropriate answer from the options given below :

During the transition of electron from state A to state C of a Bohr atom, the wavelength of emitted radiation is $2000 Å$ and it becomes $6000 Å$ when the electron jumps from state B to state C. Then the wavelength of the radiation emitted during the transition of electrons from state A to state B is

 For the circuit shown above, equivalent GATE is :

Considering the Bohr model of hydrogen like atoms, the ratio of the ratio of the radius $5^{\text {th }}$ orbit of the electron in $\mathrm{Li}^{2+}$ and $\mathrm{He}^{+}$is

An electron in the ground state of the hydrogen atom has the orbital radius of $5.3 \times 10^{-11} \mathrm{~m}$ while that for the electron in third excited state is $8.48 \times 10^{-10} \mathrm{~m}$. The ratio of the de Broglie wavelengths of electron in the excited state to that in the ground state is

Which of the following circuits represents a forward biased diode?  Choose the correct answer from the options given below :

The radiation pressure exerted by a 450 W light source on a perfectly reflecting surface placed at 2 m away from it, is :

The truth table of the given circuit diagram is :