Modern Physics PYQ — Page 15

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:

A nucleus of mass $M$ at rest splits into two parts having masses $\frac{{M}^{'}}{3}$ and $\frac{2{M}^{'}}{3}({M}^{'}<M)$. The ratio of de Broglie wavelength of two parts will be

A logic gate circuit has two inputs $A$ and $B$ and output $Y$. The voltage waveforms of $A,B$ and $Y$ are shown below  The logic gate circuit is

When light of frequency twice the threshold frequency is incident on the metal plate, the maximum velocity of emitted electron is ${v}_{1}$. When the frequency of incident radiation is increased to five times the threshold value, the maximum velocity of emitted electron becomes ${v}_{2}$. If ${v}_{2}=x{v}_{1}$, the value of $x$ will be _____ .

$\sqrt{{d}_{1}}$ and $\sqrt{{d}_{2}}$ are the impact parameters corresponding to scattering angles $60^{\circ}$ and $90^{\circ}$ respectively, when an $\alpha$ particle is approaching a gold nucleus. For ${d}_{1}=x{d}_{2}$, the value of $x$ will be _____ .

The photodiode is used to detect the optical signals. These diodes are preferably operated in reverse biased mode because

A parallel beam of light of wavelength $900\mathrm{nm}$ and intensity $100{\mathrm{Wm}}^{-2}$ is incident on a surface perpendicular to the beam. The number of photons crossing $1{\mathrm{cm}}^{2}$ area perpendicular to the beam in one second is

The electric field at a point associated with a light wave is given by $E=200[\mathrm{sin}(6\times {10}^{15})t+\mathrm{sin}(9\times {10}^{15})t]{\mathrm{Vm}}^{-1}$ Given: $h=4.14\times {10}^{-15}\mathrm{eVs}$ If this light falls on a metal surface having a work function of $2.50\mathrm{eV}$, the maximum kinetic energy of the photoelectrons will be

The value of power dissipated across the zener diode $({V}_{z}=15V)$ connected in the circuit as shown in the figure is $x\times {10}^{-1}W$.  The value of $x$ to the nearest integer is _______.

In Bohr's atomic model, the electron is assumed to revolve in a circular orbit of radius $0.5\overset{\circ }{A}.$ If the speed of electron is $2.2\times {10}^{6}m{s}^{-1}.$ Then the current associated with the electron will be__________ $\times {10}^{-2}\mathrm{mA}.$ [Take $\pi$ as $\frac{22}{7}]$

 The logic circuit shown above is equivalent to :

The radiation corresponding to $3\rightarrow 2$ transition of a hydrogen atom falls on a gold surface to generate photoelectrons. These electrons are passed through a magnetic field of $5\times {10}^{-4}T$. Assume that the radius of the largest circular path followed by these electrons is $7\mathrm{mm}$, the work function of the metal is: (Mass of electron $=9.1\times {10}^{-31}\mathrm{kg}$)

An $\alpha$ particle and a proton are accelerated from rest by a potential difference of $200V$. After this, their de Broglie wavelengths are ${\lambda }_{\alpha }$ and ${\lambda }_{p}$ respectively. The ratio $\frac{{\lambda }_{p}}{{\lambda }_{\alpha }}$ is :

A zener diode having zener voltage $8V$ and power dissipation rating of $0.5W$ is connected across a potential divider arranged with maximum potential drop across zener diode is as shown in the diagram. The value of protective resistance ${R}_{p}$ is _____$\Omega .$ 

The decay of a proton to neutron is :

Zener breakdown occurs in a $p-n$ junction having $p$and $n$ both:

The ${K}_{\alpha }$ X-ray of molybdenum has wavelength $0.071\mathrm{nm}$. If the energy of a molybdenum atom with a $K$ electron knocked out is $27.5\mathrm{keV}$, the energy of this atom when an $L$ electron is knocked out will be $\mathrm{keV}$. (Round off to the nearest integer ) $[h=4.14\times {10}^{-15}\mathrm{eV}s,c=3\times {10}^{8}{ms}^{-1}]$

The stopping potential for electrons emitted from a photosensitive surface illuminated by light of wavelength $491\mathrm{nm}$ is $0.710V.$ When the incident wavelength is changed to a new value, the stopping potential is $1.43V.$ The new wavelength is :

A zener diode of power rating $2W$ is to be used as a voltage regulator. If the zener diode has a breakdown of $10V$ and it has to regulate voltage fluctuated between $6V$ and $14V$, the value of ${R}_{s}$ for safe operation should be _____ $\Omega$ . 

A certain metallic surface is illuminated by monochromatic radiation of wavelength $\lambda$. The stopping potential for photoelectric current for this radiation is $3{V}_{0}.$ If the same surface is illuminated with a radiation of wavelength $2\lambda ,$ the stopping potential is ${V}_{0}.$ The threshold wavelength of this surface for photoelectric effect is___________$\lambda .$

The binding energy per nucleon is maximum for:

The stopping potential in the context of photoelectric effect depends on the following property of incident electromagnetic radiation:

For extrinsic semiconductors; when doping level is increased;

A circuit is arranged as shown in figure. The output voltage ${V}_{o}$ is equal to __________ $V.$