List of top Physics Questions

An ideal refrigerator has a freezer at a temperature of $-13^{\circ} C$. The coefficient of performance of the engine is $5$. The temperature of the air (to which heat is rejected) will be

A point source of light is placed $4 \,m$ below the surface of water of refractive index $\frac{5}{3}$. The minimum diameter of a disc, which should be placed over the source, on the surface of water to cut-off all right coming out of water is

The magnitude of electric field intensity $E$, such that an electron placed in it would experience an electrical force equal to its weight, is given by

A ball is dropped from height h and another from $2h.$ The ratio of time taken by the two balls to reach the ground is

Fast neutrons can easily be solved down by

Which of the following is not an example of perfectly inelastic collision

A steady current flow in a metallic conductor of non-uniform cross-section. The quantity/quantities remaining constant along the whole length of the conductor is/are

A cube has a side of length $1.2 \times 10^{-2} m$. Calculate its volume.

The work done in placing a charge of $8 \times 10^{-18} \, C$ on a capacitor of capacity $100\, \mu F$ is

If a new planet is discovered rotating around sun with the orbital radius double that of the earth, then what will be its time period? (in earth's days) (Take $\sqrt{2}=1.4$ )

The Poisson's ratio of a material is $0.5$. If a force is applied to a wire of this material, there is a decrease in the cross-sectional area by $4 \%$. The percentage increase in the length is:

A toroidal solenoid with an air core has an average radius of $15 \,cm$, area if crosssection $12\, cm ^{2}$ and $1200$ turns. Ignoring the field variation across the cross- section of the toroid, the self-inductance of the toroid is:-

A passenger in an open car travelling at $30\, m / s$ throws a ball out over the bonnet. Relative to the car the initial velocity of the ball is $20 m / s$ at $60^{\circ}$ to the horizontal. The angle of projection of the ball with respect to the horizontal road will be :

Natural length of a spring is $60 \,cm$ and its spring constant is $4000 \,N / m$. A mass of $20\, kg$ is hung from it. The extension produced in the spring is $\left(\right.$ take $\left.g=9.8 \,m / s ^{2}\right)$ :

The speed of earth's rotation about its axis is co. Its speed increases to $ x $ times to make effective acceleration due to gravity equal to zero at the equator, $ x $ is

A wooden cube (density of wood $'d'$) of side $'\ell'$ floats in a liquid of density $'\rho'$ with its upper and lower surfaces horizontal. If the cube is pushed slightly down and released, it performs simple harmonic motion of period $'T'$. Then, $'T'$ is equal to :

The speed of earth?s rotation about its axis is $\omega$. Its speed is increased to $x$ times to make the effective acceleration due to gravity equal to zero at the equator. Then $x$ is

A boy has $60\, kg$ weight. He wants to swim in a river with the help of a wooden log. If relative density of wood is $0.6$. What is the minimum volume of wooden log? (Density of river water is $1000\, kg / m ^{3}$ )

A parallel beam of light of wavelength $6000\, ?$ gets diffracted by a single slit of width $0.3 \,mm$. The angular position of the first minima of diffracted light is

Consider the following statements in case of Young's double slit experiment. a) A slit $S$ is necessary if we use an ordinary extended source of light. b) A slit $S$ is not needed if we use an ordinary but well collimated beam of light. c) A slit $S$ is not needed if we use a spatially coherent source of light. Which of the above statements are correct?

$A \,1 \,N$ pendulum bob is held at an angle $\theta$ from the vertical by a $2\, N$ horizontal force $F$ as shown in the figure. The tension in the string supporting the pendulum bob (in newton) is

Magnitude of drift velocity per unit electric field is

In photoelectric emission process from a metal of work function $1.8\, eV$, the kinetic energy of most energetic electrons is $0.5\, eV$. The corresponding stopping potential is

A theatre of volume $100 \times 40 \times 10m^3$ can accommodate 1000 visitors. The reverberation time of the theatre when empty is 8.5 s. If the theatre is now filled with 500 visitors, occupying the front-half seats, the reverberation time changes to 6.2 s. The average absorption coeficient of each visitor is nearly