List of top Physics Questions

The efficiency of an ideal heat engine working between the freezing point and boiling point of water, is
The fundamental frequency in an open organ pipe is equal to the third harmonic of a closed organ pipe. If the length of the closed organ pipe is 20 cm, the length of the open organ pipe is
A pendulum is hung from the roof of a sufficiently high building and is moving freely to and fro like a simple harmonic oscillator. The acceleration of the bob of the pendulum is 20 m/s2 at a distance of 5 m from the mean position. The time period of oscillation is
A student measured the diameter of a small steel ball using a screw gauge of least count 0.001 cm. The main scale reading is 5 mm and zero of circular scale division coincides with 25 divisions above the reference level. If screw gauge has a zero error of – 0.004 cm, the correct diameter of the ball is
An electron falls from rest through a vertical distance h in a uniform and vertically upward directed electric field E. The direction of electric field is now reversed, keeping its magnitude the same. A proton is allowed to fall from rest in it through the same vertical distance h. The time of fall of the electron, in comparison to the time of fall of the proton is
Unpolarised light is incident from air on a plane surface of a material of refractive index ‘μ’. At a particular angle of incidence ‘i’, it is found that the reflected and refracted rays are perpendicular to each other. Which of the following options is correct for this situation ?
An astronomical refracting telescope will have large angular magnification and high angular resolution, when it has an objective lens of
The volume (V) of a monatomic gas varies with its temperature (T), as shown in the graph. The ratio of work done by the gas, to the heat absorbed by it, when it undergoes a change from state A to state B, is
ratio of work done by the gas, to the heat absorbed
Two wires are made of the same material and have the same volume. The first wire has cross-sectional area A and the second wire has cross-sectional area 3A. If the length of the first wire is increased by \(\Delta l\) on applying a force F, how much force is needed to stretch the second wire by the same amount ?
The power radiated by a black body is P and it radiates maximum energy at wavelength, λ0 . If the temperature of the black body is now changed so that it radiates maximum energy at wavelength \(\frac{3}{4}\lambda_0\), the power radiated by it becomes nP. The value of n is
A thin diamagnetic rod is placed vertically between the poles of an electromagnet. When the current in the electromagnet is switched on, then the diamagnetic rod is pushed up, out of the horizontal magnetic field. Hence the rod gains gravitational potential energy. The work required to do this comes from
In the circuit shown in the figure, the input voltage Vi is 20V, VBE = 0 and VCE = 0. The values of IB , IC and β are given by
the input voltage Vi is 20V, VBE = 0 and VCE = 0
The ratio of kinetic energy to the total energy of an electron in a Bohr orbit of the hydrogen atom, is
The refractive index of the material of a prism is √2 and the angle of the prism is 30°. One of the two refracting surfaces of the prism is made a mirror inwards, by silver coating. A beam of monochromatic light entering the prism from the other face will retrace its path (after reflection from the silvered surface) if its angle of incidence on the prism is
A small sphere of radius ‘r’ falls from rest in a viscous liquid. As a result, heat is produced due to viscous force. The rate of production of heat when the sphere attains its terminal velocity, is proportional to
A sample of 0.1 g of water at 100°C and normal pressure (1.013 × 105 Nm-2 ) requires 54 cal of heat energy to convert to steam at 100°C. If the volume of the steam produced is 167.1 cc, the change in internal energy of the sample, is
A body of mass 2 kg thrown vertically upward from the ground with a velocity of $8 \, ms^{-1}$ reaches a maximum height of 3 in. The work done by the air resistance is_______ (Acceleration due to gravity = $10 \, ms^{-2}$)
A force is applied to an object that is free to move. Which of the following statements is correct?
A rigid bar of mass 15 kg is supported symmetrically by three wires each 2 m long. Those at each end are of copper and the middle one is of iron. Determine the ratio of their diameters if each is to have the tension.
An astronaut is standing on an asteroid when he accidentally drops a wrench. He observes that the gravitational acceleration on the asteroid is 2.4 m/s². If he had thrown the wrench at an upward angle instead, he would have found the gravitational acceleration on the asteroid to be
The two-dimensional cube in the diagram below has charged objects placed at the corners as shown. An electron that is free to move is placed at the exact centre of the cube. In which direction will the electron move?
A body takes 5 min for cooling from 50°C to 40°C. Its temperature comes down to 33.33°C in the next 5 min. Temperature of the surroundings is
A TV tower has a height of 100 m. How much population is covered by TV broadcast, if the average population density around the tower is \( 1000 \, {km}^{-2} \) (radius of Earth = \( 6.4 \times 10^6 \, {m} \))?
The number of neutrons released during the fission reaction \[ {n} + ^{235} {U} \longrightarrow ^{133} {Sb} + ^{99} {Nb} + {neutrons is} \]
For a monoatomic gas, work done at constant pressure is W. The heat supplied at constant volume for the same rise in temperature of the gas is