List of top Physics Questions

The magnitude of total energy and angular momentum of an electron in the \( n \)th orbit of a Bohr atom is denoted by \( E_n \) and \( L_n \), respectively. Then
A ray of light passes through an equilateral prism such that the angle of incidence is equal to angle of emergence and each of these angles is equal to \( \frac{1}{3} \)rd the angle of prism. The angle of deviation is
A uniform rod AB of mass \( m \) and length \( l \) is at rest on a smooth horizontal surface. An impulse \( P \) is applied to the end B. The time taken by the rod to turn through a right angle is
A cylindrical magnetic rod has length 5 cm and diameter 1 cm. It has uniform magnetization \( 5 \times 10^3 \, \text{A/m} \). Its net magnetic dipole moment is nearly
In communication system, the range for line of sight propagation in case of earth is \( d \), for the height of antenna \( h \). If \( h \) is doubled then the new range is
A uniform metal wire of length \( L \), mass \( M \) and density \( \rho \) is under a tension \( T \). If the speed of transverse wave along the wire is \( V \), then area of cross-section of the wire is
A glass convex lens is of refractive index 1.55 with both faces of same radius of curvature. What will be the radius of curvature if focal length is to be 20 cm?
From a disc of mass \( M \) and radius \( R \), a circular hole of diameter \( R \) is cut whose rim passes through the centre. The moment of inertia of the remaining part of the disc about perpendicular axis passing through the centre is
Due to surface tension, the excess pressure inside a smaller drop is 9 units. If 27 smaller drops combine, then the excess pressure inside the bigger drop is
An alternating e.m.f. is given by \( e = e_0 \sin \omega t \). In what time the e.m.f. will have half its maximum value, if \( e_0 \) starts from zero? (T = Time period)
The polarising angle for a transparent medium is \( \theta \) and \( v \) is the speed of light in that medium, then relation between \( \theta \) and \( v \) is (c = velocity of light)
What should be the velocity of earth due to rotation about its own axis so that the weight at equator becomes \( \frac{1}{25} \) of initial value?
(Radius of Earth on equator = 6400 km, \( g = 10 \, \text{m/s}^2 \), \( \cos 0^\circ = 1 \))
In energy band diagram of insulators, a band gap and the conduction band is respectively
Light of incident frequency 2 times the threshold frequency is incident on a photosensitive material. If the incident frequency is made \( \frac{1}{3} \)rd and intensity is doubled then the photoelectric current will
If a gas is compressed isothermally then the r.m.s. velocity of the molecules
When a photosensitive surface is irradiated by lights of wavelengths \( \lambda_1 \) and \( \lambda_2 \), kinetic energies of emitted photoelectrons are \( E_1 \) and \( E_2 \) respectively. The work function of the photosensitive surface is
A circular and a square coil is prepared from two identical metal wires and a current is passed through them. Ratio of magnetic dipole moment associated with circular coil to that with square coil is
Two galvanometers 'G1' and 'G2' require 2 mA and 3 mA respectively to produce the same deflection. Then
The length of seconds pendulum is 1 m on the earth. If the mass and diameter of the planet is double that of the earth, then the length of the seconds pendulum on the planet will be
A body of mass 5 kg is moving in a straight line. The relation between its displacement and time is \( x = (t^3 - 2t - 10) \) m. What is the force acting on it at the end of 5 seconds?
A steel wire of length \( L \) and area of cross-section \( A \) is suspended from rigid support. If \( Y \) is the Young's modulus of material of the wire and \( \alpha \) is the coefficient of linear expansion, then the increase in tension when temperature falls by \( t^\circ C \) is
Let \( \mu_1 \) and \( \mu_2 \) be the refractive indices of two media. \( v_1 \) and \( v_2 \) are the velocities of light in the media respectively. Which one of the following relations is TRUE?
The materials having negative magnetic susceptibility are
A toroid has a non-ferromagnetic wire of inner radius \( r_1 \) and outer radius \( r_2 \), around which \( N \) turns of wire are wound. If the current in the wire is \( I \), then the magnetic field inside the toroid is
A horizontal spring executes S.H.M. with amplitude \( A_1 \), when mass \( m_1 \) is attached to it. When it passes through mean position, another mass \( m_2 \) is placed on it. Both masses move together with amplitude \( A_2 \). Therefore \( A_2 : A_1 \) is