List of top Physics Questions

The dimensional formula of Planck’s constant is
An unpolarised beam of light incidents on a group of three polarising sheets arranged such that the angle between the axes of any two adjacent sheets is $30^\circ$. The ratio of the intensities of polarised light emerging from the second and third sheets is
The minimum length of an antenna to transmit a signal of frequency \( 3 \text{ kHz} \) is
The wavelength of spectral line corresponding to electron transition \( n = 3 \) to \( n = 2 \) for \( \text{Li}^{2+} \) ion is \( \lambda \,\text{nm} \). What is the wavelength (in nm) corresponding to electron transition \( n = 4 \) to \( n = 1 \) for \( \text{He}^+ \) ion?
If a capacitor of 500 nF is connected to an AC source of frequency 1 kHz, then the capacitive reactance of the capacitor is
If the collector and base currents of a transistor in common emitter configuration are 5 mA and 50 \(\mu\)A, then the current amplification factor of the transistor is
In the circuit of resistors shown in the figure, the effective resistance between points A and B is
effective resistance between points A and B is
The capacitance of a solid sphere of radius 18 cm is
The focal length of a convex lens immersed in a liquid of refractive index 1.2 is \( f_1 \) and its focal length when immersed in another liquid of refractive index 1.25 is \( f_2 \). If the refractive index of the material of the lens is 1.5, then \( f_1 : f_2 = \)
A spherical black body of radius 12 cm at a temperature of \(T\) K radiates a power of 400 W. If the radius of the sphere is doubled and absolute temperature is halved, then the power radiated by the body is
Three point charges +10 µC, +20 µC, and +40 µC are placed at the vertices of an equilateral triangle of side 1 m. The electrostatic potential energy of the system of the charges is
If two temperatures on Celsius scale differ by \( 25^\circ \), then the difference of those two temperatures on Fahrenheit scale is
During adiabatic expansion process, if the temperature of 4 moles of a monoatomic gas is decreased by \(100^\circ C\), then the work done by the gas is
(Universal gas constant \(R = 8.3 \, \text{J/mol·K}\))
If the amplitudes of a damped harmonic oscillator at times 3 and 6 seconds are 6 cm and 4 cm respectively, then the initial amplitude of the oscillator is
A body of mass 2 kg starts moving from the origin (0, 0) with an initial velocity of \( (4\hat{i} + 4\hat{j})\ \text{ms}^{-1} \). A constant force of \( -20\hat{j} \ \text{N} \) is applied on the body. When the Y-coordinate of the position of the body becomes zero again, then its X-coordinate is
For a body in simple harmonic motion, the relation between force \( F \) (in Newton) acting on the body and its displacement \( y \) (in metre) is given as \( F + 3y = 0 \). If the time period of oscillation of the body is \( \pi \) s, then its mass is
A person walks up an escalator at rest in a time of 60 s. When standing on the same escalator now moving with a uniform speed, he is carried up in a time of 30 s. The time taken for him to walk up the moving escalator is
If a body is projected horizontally from a height of 50 m with a speed of 20 m/s, then its speed after a time of 1.5 s is
(Acceleration due to gravity \( g = 10\ \text{m/s}^2 \))
In a transistor, if the emitter and collector currents are respectively 2 mA and 1.95 mA, then the base current is
The current in a coil decreases from 5 A to zero in a time of 0.1 s. If an average emf of 200 V is induced, then the self inductance of the coil is
If the radius of a circular coil is doubled and the number of turns is halved, then the magnetic field at the centre of the coil for the same current is
If a particle of mass \( 6 \times 10^{-30} \) kg is moving with a speed of \( 5.5 \times 10^5 \text{ m s}^{-1} \), then the de Broglie wavelength of the particle is
(Planck's constant = \( 6.6 \times 10^{-34} \text{ J s} \))
In a hydrogen atom, if an electron makes a transition from the fourth orbit to the second orbit, then the wavelength of the emitted radiation is: (R = Rydberg constant)
A sphere of radius R and charge 'Q' is placed inside an imaginary sphere of radius 2R such that the centres of two spheres coincide. The electric flux linked with the imaginary sphere is
In the given circuit, if the current through 4 $\Omega$ resistor is zero, then the value of the resistance $R$ is:
current through 4 Ω resistor is zero,