Browse and search thousands of solved questions for your preparation.
Free questions with full explanations — locked behind signup to protect quality.
An electromagnetic wave of wavelength '$\lambda$' is incident on a photosensitive surface of negligible work function. If 'm' mass is of photoelectron emitted from the surface has de-Broglie wavelength $\lambda_d$, then
The ratio of frequencies of fundamental harmonic produced by an open pipe to that of closed pipe having the same length is
In a Young's double slit experiment, a student observes $8$ fringes in a certain segment of screen when a monochromatic light of $600\text{ nm}$ wavelength is used. If the wavelength of light is changed to $400\text{ nm}$, then the number of fringes he would observe in the same region of the screen is
A parallel plate capacitor has a uniform electric field $\vec{E}$ in the space between the plates. If the distance between the plates is '$d$' and the area of each plate is '$A$', the energy stored in the capacitor is ($\varepsilon_0$ = permittivity of free space)
A particle is released from height S from the surface of the Earth. At a certain height its kinetic energy is three times its potential energy. The height from the surface of earth and the speed of the particle at that instant are respectively
A thick current carrying cable of radius 'R' carries current 'I' uniformly distributed across its cross-section. The variation of magnetic field B(r) due to the cable with the distance 'r' from the axis of the cable is represented by
A cup of coffee cools from $90^{\circ}C$ to $80^{\circ}C$ in $t$ minutes, when the room temperature is $20^{\circ}C$. The time taken by a similar cup of coffee to cool from $80^{\circ}C$ to $60^{\circ}C$ at a room temperature same at $20^{\circ}C$ is
A uniform rod of length $200 \text{ cm}$ and mass $500 \text{ g}$ is balanced on a wedge placed at $40 \text{ cm}$ mark. A mass of $2 \text{ kg}$ is suspended from the rod at $20 \text{ cm}$ and another unknown mass '$m$' is suspended from the rod at $160 \text{ cm}$ mark as shown in the figure. Find the value of '$m$' such that the rod is in equilibrium. ($g = 10 \text{ m/s}^2$)
A car starts from rest and accelerates at $5\text{ m/s}^2$. At $t = 4\text{ s}$, a ball is dropped out of a window by a person sitting in the car. What is the velocity and acceleration of the ball at $t = 6\text{ s}$? (Take $g = 10\text{ m/s}^2$)
A particle moving in a circle of radius $R$ with a uniform speed takes a time $T$ to complete one revolution. If this particle were projected with the same speed at an angle $\theta$ to the horizontal, the maximum height attained by it equals $4R$. The angle of projection, $\theta$, is then given by :
A wheatstone bridge is used to determine the value of unknown resistance X by adjusting the variable resistance Y as shown in the figure. For the most precise measurement of X, the resistances P and Q
When two monochromatic lights of frequency, $Q$ and $\frac{Q}{2}$ are incident on a photoelectric metal, their stopping potential becomes $\frac{V_s}{2}$ and $V_s$ respectively. The threshold frequency for this metal is
When light propagates through a material medium of relative permittivity $\epsilon_r$ and relative permeability $\mu_r$, the velocity of light, $v$ is given by (c-velocity of light in vacuum)
From Ampere's circuital law for a long straight wire of circular cross-section carrying a steady current, the variation of magnetic field in the inside and outside region of the wire is
An electric dipole is placed at an angle of $30^\circ$ with an electric field of intensity $2 \times 10^5$ N C$^{-1}$. It experiences a torque equal to 4 N m. Calculate the magnitude of charge on the dipole, if the dipole length is 2 cm.
A shell of mass $m$ is at rest initially. It explodes into three fragments having mass in the ratio $2:2:1$. If the fragments having equal mass fly off along mutually perpendicular directions with speed $v$, the speed of the third (lighter) fragment is
An ideal gas undergoes four different processes from the same initial state as shown in the figure below. Those processes are adiabatic, isothermal, isobaric and isochoric. The curve which represents the adiabatic process among 1, 2, 3 and 4 is
Given below are two statements: Statement I: Photovoltaic devices can convert optical radiation into electricity. Statement II: Zener diode is designed to operate under reverse bias in breakdown region. In the light of the above statements, choose the most appropriate answer from the options given below.
Two transparent media A and B are separated by a plane boundary. The speed of light in those media are $1.5 \times 10^8$ m/s and $2.0 \times 10^8$ m/s, respectively. The critical angle for a ray of light for these two media is
A wire carrying a current $I$ along the positive x-axis has length $L$. It is kept in a magnetic field $\vec{B} = (2\hat{i} + 3\hat{j} - 4\hat{k}) \text{ T}$. The magnitude of the magnetic force acting on the wire is