Modern Physics PYQ — Page 20

Given the masses of various atomic particles ${m}_{P}=1,0072 u$, ${m}_{n}=1,0087 u$, ${m}_{e}=0.000548 u$, ${m}_{\bar{v}}=0$, ${m}_{d}=2.0141 u$, where $p=$proton, $n\equiv$neutron, $e\equiv$electron, $\bar{v}\equiv$antineutrino and $\bar{d}\equiv$deuteron. Which of the following process is allowed by momentum and energy conservation :

An electron, a doubly ionized helium ion ($He^{++}$) and proton are having the same kinetic energy. The relation between their respective de-Broglie wavelength ${\lambda }_{{e}^{*}}{\lambda }_{{\mathrm{He}}^{++}}$ and ${\lambda }_{p}$ is :

Identify the correct output signal $Y$ in the given combination of gates (as shown $n$) for the given inputs $AandB$  

In the circuit shown below, is working as a $8Vdc$ regulated voltage source. When $12V$ is used as an input, the power dissipated (in $mW$ ) in each diode is (Considering both zener diodes are identical) 

The de Broglie wavelength of an electron accelerated through a potential difference of 100 V is approximately:

An electron (mass $m$ ) with initial velocity $\vec{v}={v}_{0}\hat{i}+{v}_{0}\hat{j}$ is in an electric filed $\vec{E}=-{E}_{0}\hat{k}.$ If ${\lambda }_{0}$ is initial de-Broglie wavelength of electron, its de-Broglie wave length at time $t$ is given by:

Boolean relation at the output stage- $Y$ for the following circuit is: 

If a semiconductor photo diode can detect a photon with a maximum wavelength of $400\mathrm{nm}$, then its band gap energy is: Planck's constant $h=6.63\times {10}^{-34}J.s$ Speed of light $c=3\times {10}^{8}m{s}^{-1}$

Find the Binding energy per nucleon for $\mathrm{Sn}50120$. Mass of proton ${m}_{p}=1.00783U$, mass of neutron ${m}_{n}=1.00867U$ and mass of tin nucleus ${m}_{\mathrm{sn}}=119.902199U$. (take $1U=931MeV$)

Both the diodes used in the circuit shown are assumed to be ideal and have negligible resistance when these are forward biased. Built in potential in each diode is $0.7V$. For the input voltages shown in the figure, the voltage (in Volts) at point A is ________ 

The radius $R$ of a nucleus of mass number $A$ can be estimated by the formula $R=(1.3\times {10}^{-15}){A}^{1/3}m$. It follows that the mass density of n nucleus is of the order of: $({M}_{prot}\cong {M}_{\text{neut }}\simeq 1.67\times {10}^{-27}\mathrm{kg})$

In a photoelectric effect experiment, the graph of stopping potential $V$ versus reciprocal of wavelength obtained is shown in the figure. As the intensity of incident radiation is increased : 

The truth table for the circuit given in the figure is: 

A $H{e}^{+}$ ion is in its first excited state. Its ionization energy is:

Light is incident normally on a completely absorbing surface with an energy flux of $25 W c{m}^{-2}$ . If the surface has an area of $25 c{m}^{2}$ , the momentum transferred to the surface in $\text{40} \text{min}$ time duration will be:

$Ge$ and $Si$ diodes start conducting at $0.3 V$ and $0.7 V$ respectively. In the following figure if $Ge$ diode connection are reversed, the value of ${V}_{0}$ changes by: (assume that the Ge diode has large breakdown voltage) 

The electron in a hydrogen atom first jumps from the third excited state to the second excited state and subsequently to the first excited state. The ratio of the respective wavelengths $\frac{{\lambda }_{1}}{{\lambda }_{2}}$ of the photons emitted in this process is:

When a certain photosensitive surface is illuminated with a monochromatic light of frequency $\nu ,$ the stopping potential of the photo current is $-\frac{{V}_{0}}{2}.$ When the surface is illuminated by monochromatic light of frequency $\frac{\nu }{2},$ the stopping potential is $-{V}_{0}.$ The threshold frequency for photoelectric emission is

Two particles move at right angle to each other. Their de Broglie wavelengths are ${\lambda }_{1}$ and ${\lambda }_{2}$ respectively. The particles suffer perfectly inelastic collision. The de Broglie wavelength $\lambda$ of the final particle, is given by:

A nucleus $A,$ with a finite de-broglie wavelength ${\lambda }_{A},$ undergoes spontaneous fission into two nuclei $B$ and $C$ of equal mass. $B$ flies in the same direction as that of $A,$ while $C$ flies in the opposite direction with a velocity equal to half of that of $B.$ The de-Broglie wavelengths ${\lambda }_{B}$ and ${\lambda }_{C}$ of B and C are respectively:

To get output '1' at $R,$ for the given logic gate circuit the input values must be: 

The figure represents a voltage regulator circuit using a Zener diode. The breakdown voltage of the Zener diode is $6 V$ and the load resistance is, ${R}_{L}=4 k\Omega$ . The series resistance of the circuit is ${R}_{i}=1 k\Omega$ . If the battery voltage ${V}_{B}$ varies from $8 V$ to $16 V$ , what are the minimum and maximum values of the current through Zener diode? 

A particle $A$ of mass $m$ and charge $q$ is accelerated by a potential difference of $50 V.$ Another particle $B$ of mass $4m$ and charge $q$ is accelerated by a potential difference of $2500 V.$ The ratio of de-Broglie wavelengths $\frac{{\lambda }_{A}}{{\lambda }_{B}}$ is close to:

Radiation coming from transitions $n=2$ to $n=1$ of hydrogen atoms fall on ${He}^{+}$ ions in $n=1$ and $n=2$ states. The possible transition of helium ions as they absorb energy from the radiation is: