Modern Physics PYQ — Page 6

If in a p-n junction, a square input signal of $10V$ is applied as shown, then the output across ${R}_{L}$ will be 

If radius of the $A1327l$ nucleus is taken to be ${R}_{Al}$ then the radius of $Te53125$ nucleus is nearly

In the spectrum of hydrogen, the ratio of the longest wavelength in the Lyman series to the longest wavelength in the Balmer series is:

A photoelectric surface is illuminated successively by monochromatic light of wavelength $\lambda$ and $\frac{\lambda }{2}$. If the maximum kinetic energy of the emitted photoelectrons in the second case is 3 times that in the first case, the work function of the surface of the material is: ($h$ = Planck's constant, $c$ = speed of light)

Which of the following figures represent the variation of particle momentum and the associated de-Broglie wavelength?

Consider third orbit of ${\mathrm{He}}^{+}$ (helium), using non-relativistic approach, the speed of electron in this orbit will be given constant $K{\text{=9×10}}^{\text{9}}$, $Z=2$ and $h$ (Planck's Constant)$\text{= 6}\text{.6 }\times {\text{ 10}}^{-34}\text{ J s}$

Which logic gate is represented by the following combination of logic gates? 

The barrier potential of a p-n junction depends on: $(a)$ type of semi-conductor material $(b)$ amount of doping $(c)$ temperature Which one of the following is correct?

Hydrogen atom in ground state is excited by a monochromatic radiation of $\lambda =975 Å.$ Number of spectral lines in the resulting spectrum emitted will be:

A radio isotope ‘$X$’ with a half life $1.4\times {10}^{9}$ years decays to ‘$Y$’ which is stable. A sample of the rock from a cave was found to contain ‘$X$’ and ‘$Y$’ in the ratio $1:7$. The age of the rock is

When the energy of the incident radiation is increased by $20%,$ the kinetic energy of the photoelectrons emitted from a metal surface increased from emitted $0.5 eV$ to $0.8 eV.$ The work function of the metal is:

If the kinetic energy of the particle is increased to 16 times its previous value, the percentage change in the de-Broglie wavelength of the particle is:

The given graph represents $V$ - $I$ characteristic for a semiconductor device.  Which of the following statement is correct?

The Binding energy per nucleon of $Li37$ and $He24$ nucleon are $5.60 MeV$ and $7.06 M\mathrm{eV}$, respectively. In the nuclear reaction ${ }_{3}^{7}Li+{ }_{1}^{1}H\rightarrow { }_{2}^{4}He+{ }_{2}^{4}He+Q$, the value of energy $Q$ released is

An electron in hydrogen atom makes a transition $n_1 \rightarrow n_2$ where $n_1$ are principle quantum numbers of the two states. Assuming Bohr's model to be valid, the time period of the electron in the initial state is eight times that in the final state. The possible values of $n_1$ and $n_2$ are:

Ratio of longest wavelengths corresponding to Lyman and Balmer series in hydrogen spectrum is

The output from a NAND gate is divided into two in parallel and fed to another NAND gate. The resulting gate is a: 

$\alpha$-particle, $\beta$-particle and $\gamma$-rays are all having same energy. Their penetrating power in a given medium in incresing order will be:

A certain mass of hydrogen is changed to helium by the process of fusion. The mass defect in fusion reaction is $0.02866 \mathrm{u}$. The energy liberated per $u$ is (given $1 \mathrm{u}=931 \mathrm{MeV}$ )

The de-Broglie wavelength of neutrons in thermal equilibrium at temperature $T$ is:

In a $n$-type semiconductor, which of the following statement is true?

How does the Binding Energy per nucleon vary with the increase in the number of nucleons?

A source of light is placed at a distance of $50 \mathrm{~cm}$ from a photo cells and the stopping potential is found to be $\mathrm{V}_{0^*}$. If the distance between the light source and photo cells is made $25 \mathrm{~cm}$, the new stopping potential will be:

For photoelectric emission from certain metal the cut-off frequency is $v$. If radiation of frequency $2 \mathrm{v}$ impinges on the metal plate, the maximum possible velocity of the emitted electron will be ( $m$ is the electron mass)