Modern Physics PYQ — Page 13

Let ${K}_{1}$ and ${K}_{2}$ be the maximum kinetic energies of photo-electrons emitted when two monochromatic beams of wavelength ${\lambda }_{1}$ and ${\lambda }_{2}$, respectively are incident on a metallic surface. If ${\lambda }_{1}=3{\lambda }_{2}$ then :

With reference to the observations in photo-electric effect, identify the correct statements from below: A. The square of maximum velocity of photoelectrons varies linearly with frequency of incident light. B. The value of saturation current increases on moving the source of light away from the metal surface. C. The maximum kinetic energy of photo-electrons decreases on decreasing the power of LED (light emitting diode) source of light. D. The immediate emission of photo-electrons out of metal surface can not be explained by particle nature of light/electromagnetic waves. E. Existence of threshold wavelength can not be explained by wave nature of light/electromagnetic waves. Choose the correct answer from the options given below:

A $8V$ Zener diode along with a series resistance $R$ is connected across a $20V$ supply (as shown in the figure). If the maximum Zener current is $25\mathrm{mA}$, then the minimum value of $R$ will be _____ $\Omega$. 

In the circuit, the logical value of $A=1$ or $B=1$ when potential at $A$ or $B$ is $5V$ and the logical value of $A=0$ or $B=0$ when potential at $A$ or $B$ is $0V$.  The truth table of the given circuit will be :

A potential barrier of $0.4V$ exists across a p-n junction. An electron enters the junction from the $n$-side with a speed of $6.0\times {10}^{5}{ms}^{-1}$. The speed with which electron enters the $p$ side will be $\frac{x}{3}\times {10}^{5}{ms}^{-1}$, then the value of $x$ is _____.: (Given mass of electron $=9\times {10}^{-31}\mathrm{kg}$, charge on electron $=1.6\times {10}^{-19}C$.)

Identify the correct Logic Gate for the following output $(Y)$ of two inputs $A$ and $B$. 

As per the given circuit, the value of current through the battery will be _____ A. 

An electron with speed $v$ and a photon with speed $c$ have the same de-Broglie wavelength. If the kinetic energy and momentum of electron are ${E}_{e}$ and ${P}_{e}$ and that of photon are ${E}_{ph}$ and ${P}_{ph}$ respectively. Which of the following is correct?

Two ideal diodes are connected in the network as shown in figure. The equivalent resistance between $A$ and $B$ is _____ $\Omega .$ 

The kinetic energy of emitted electron is $E$ when the light incident on the metal has wavelength $\lambda$. To double the kinetic energy, the incident light must have wavelength:

If the potential barrier across a $p-n$ junction is $0.6V$. Then the electric field intensity, in the depletion region having the width of $6\times {10}^{-6}m$, will be _____ $\times {10}^{5}N{C}^{-1}$

Mass numbers of two nuclei are in the ratio of $4:3$. Their nuclear densities will be in the ratio of

In the given circuit the input voltage ${V}_{\mathrm{in}}$ is shown in figure. The cut-in voltage of $p-n$ junction diode (${D}_{1}$ or ${D}_{2}$) is $0.6V$. Which of the following output voltage $({V}_{0})$ waveform across the diode is correct? 

The $I-V$ characteristics of a $p-n$ junction diode in forward bias is shown in the figure. The ratio of dynamic resistance, corresponding to forward bias voltage of $2V$ and $4V$ respective is 

The momentum of an electron revolving in ${n}^{th}$ orbit is given by : (Symbols have their usual meanings)

Which of the following figure represents the variation of $\mathrm{ln}(\frac{R}{{R}_{0}})$ with $\mathrm{ln}A$ (if $R=$ radius of a nucleus and $A=$ its mass number)

A Zener of breakdown voltage ${V}_{Z}=8V$ and maximum Zener current, ${I}_{\mathrm{ZM}}=10\mathrm{mA}$ is subjected to an input voltage ${V}_{i}=10V$ with series resistance $R=100\Omega$. In the given circuit ${R}_{L}$ represents the variable load resistance. The ratio of maximum and minimum value of ${R}_{L}$ is _____ . 

The cut-off voltage of the diodes (shown in figure) in forward bias is $0.6V$. The current through the resister of $40\Omega$ is _____ $\mathrm{mA}$. 

Two streams of photons, possessing energies to five and ten times the work function of metal are incident on the metal surface successively. The ratio of the maximum velocities of the photoelectron emitted, in the two cases respectively, will be

A hydrogen atom in its ground state absorbs $10.2\mathrm{eV}$ of energy. The angular momentum of electron of the hydrogen atom will increase by the value of (Given, Planck's constant $=6.6\times {10}^{-34}\mathrm{Js}$).

The stopping potential for photoelectrons emitted from a surface illuminated by light of wavelength $6630Å$ is $0.42V$. If the threshold frequency is $x\times {10}^{13}s$, where $x$ is (nearest integer): (Given, speed light $=3\times {10}^{8}m{s}^{-1}$. Planck's constant $=6.63\times {10}^{-34}Js$)

Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R. Assertion A : The photoelectric effect does not take place, if the energy of the incident radiation is less than the work function of a metal. Reason R : Kinetic energy of the photoelectrons is zero, if the energy of the incident radiation is equal to the work function of a metal.

Identify the solar cell characteristics from the following options :

Hydrogen atom from excited state comes to the ground by emitting a photon of wavelength $\lambda$. The value of principal quantum number $n$ of the excited state will be : ( $R:$ Rydberg constant)