List of top Physics Questions

A glass prism ABC (refractive index 1.5), immersed in water (refractive index \( \frac{4}{3} \)). A ray of light is incident normally on face AB. If it is totally reflected at face AC, then

A rocket is fired from the Earth towards the Sun. At what distance from the Earth's centre, the gravitational force on the rocket is zero? Mass of the Sun = \( 2 \times 10^{30} \, \text{kg} \) and mass of the Earth = \( 6 \times 10^{24} \, \text{kg} \).
Two trains A and B of length 400 m each are moving on two parallel tracks with a uniform speed of 72 km/h in the same direction, with A ahead of speed B. The driver of B decides to overtake A and accelerates by 1 m/s². If after 50s, the guard of B just brushes past the driver of A, what was the original distance between them?
A beam of light (\( \lambda = 600 \, \text{nm} \)) from a distant source, falls on a single slit 1 mm wide and the resulting diffraction pattern is observed on a screen 2 m away. The distance between the first dark fringes on either side of the central bright fringe is:
A liquid is poured into a vessel at rest with the hole in a wall closed by a valve. It is filled to height \( H \). The distance of the hole from the top surface is \( h \). What is the horizontal acceleration required to move the vessel so that the liquid does not come out when the valve is opened (given \( l = \) length of the base)?
Which of the following factors by itself will increase the frequency at which an observer hears a sound emanating from a source?
A stretched string of length 1 m fixed at both ends, when vibrated in one loop has a frequency of 200 Hz. It is now plucked at a point situated at 25 cm from one end. The stretched string would vibrate with a frequency of:
If 10% of a radioactive substance decays in every 5 years, then the percentage of the substance that will have decayed in 20 years, will be:

Ball A moving at 12 m/s collides elastically with ball B, initially at rest as shown. If both balls have the same mass, then what is the final velocity of ball A?

If two simple pendulums first of bob mass \( M_1 \) and length \( l_1 \), and \( M_2 \) and \( l_2 \), Given \( M_1 = M_2 \) and \( l_1 = 2l_2 \), If the vibrational energies of both are same, then which of the following is correct?
A and B are at an angle of 60° with each other. Their resultant makes an angle of 45° with a. If \( b = 2 \) units, then \( a \) is:
An electron of a stationary hydrogen atom passes from the fifth energy level to the ground level. The velocity that the atom acquired as a result of photon emission will be:
The North pole of the Earth's magnetic field is at the geographical South pole. A compass is a small magnet whose North pole end is drawn in the approximate direction of
A stream of water flowing horizontally with the speed of 15 m/s gushes out of a tube of cross-sectional area \( 10^{-2} \, \text{m}^2 \) and hits a vertical wall nearby. What is the force exerted on the wall by the impact of water? Assuming it does not rebound.
A shell of mass 0.020 kg is fired by a gun of mass 100 kg. If the muzzle speed of the shell is 80 m/s, what is the recoil speed of the gun?
If torques of equal magnitudes are applied to a hollow cylinder and a solid sphere both having the same mass and radius. The cylinder is free to rotate about its standard axis of symmetry and the sphere is free to rotate about an axis passing through its center. Which of the two will acquire a greater angular speed after a given time?

Two coherent point sources \( S_1 \) and \( S_2 \) vibrating in phase emit light of wavelength \( \lambda \). The separation between them is \( 2\lambda \). The light is collected on a screen placed at a distance \( D \gg \lambda \) from the slit \( S_1 \) as shown. The minimum distance, so that intensity at \( P \) is equal to intensity at \( O \), is:

A ring of radius \( R \) is first rotated with an angular velocity \( \omega \), and then carefully placed on a rough horizontal surface. The coefficient of friction between the surface and the ring is \( \mu \). Time after which its angular speed is reduced to half is:
What will be the displacement equation of the simple harmonic motion obtained by combining the motions? Given: \[ x_1 = 2 \sin(\omega t), \quad x_2 = 4 \sin(\omega t + \frac{\pi}{2}), \quad x_3 = 6 \sin(\omega t) \]

A ball of mass \( m \) moving at a speed \( v \) makes a head-on collision with an identical ball at rest. The kinetic energy at the balls after the collision is \( \frac{3}{4} \) of the original. What is the coefficient of restitution?

The power of the combination of two lenses made by keeping the convex lens of focal length 40 cm in contact with the concave lens of focal length 25 cm, is:

A capacitor of capacitance 5 µF is connected as shown in the figure. The internal resistance of the cell is 0.5 Ω. The amount of charge on the capacitor plate is:

Use the diagram below to answer the following questions. 40 spheres of equal mass make two rings of 20 spheres each. The ring on the right has a radius twice as large as the ring on the left. At what position could a mass be placed so that the gravitational force it would experience would be the same from both rings?

The bob of a pendulum is released from a horizontal position A as shown in the figure. If the length of the pendulum is 1.5 m, what is the speed with which the bob arrives at the lower most point B, given that it dissipated 5% of its initial energy against air resistance?

Two litres of water kept in a container at \( 27^\circ \text{C} \) is heated with a coil of 1 kW. The lid of the container is open and energy dissipates at the rate of 160 J/s. If the specific heat of water is 4.2 kJ/kg, then the time taken by coil to raise the temperature of water from \( 27^\circ \text{C} \) to \( 77^\circ \text{C} \) is: