List of top Physics Questions

The average power dissipated in $A.C.$ circuit is $2$ watt. If a current flowing through a circuit is $2\, A$ and impedance is $1\, \Omega$, what is the power factor of the AC circuit ?

An object is placed at $20\,cm$ in front of a concave mirror produces three times magnified real image. What is focal length of the concave mirror ?

When the energy of the incident radiation is increased by $20 \%, $ the kinetic energy of the photoelectrons emitted from a metal surface increased from 0.5 eV to 0.8 eV. The work function of the metal is

In an ammeter 0.2% of main current passes through the galvanometer. If resistance of galvanometer is $G$, the resistance of ammeter will be

A solid cylinder of mass 50 kg and radius 0.5 m is free to rotate about the horizontal axis . A massless string is wound round the cylinder with one end attached to it and other hanging freely. Tension in the string required to produce an angular acceleration of 2 revolutions $ s^ {-2} $ is

A body of mass $(4m)$ is lying in $x-y$ plane at rest. It suddenly explodes into three pieces. Two pieces, each of mass $(m)$ move perpendicular to each other with equal speeds $(v)$. The total kinetic energy generated due to explosion is

If the temperature of the body is increased by $ 10\%, $ the percentage increase in the emitted indication will be

A uniform force of $(3\hat{i}+\hat{j}) $newton acts on a particle of mass 2 kg. Hence the particle is displaced from position $(2\hat{i}+\hat{k})$ metre to position $(4\hat{i}+3\hat{j}-\hat{k})$ metre. The work done by the force on the particle is

Choose the correct sketch of the magnetic field lines of a circular current loop shown by the dot ? and the cross ?.

The reddish appearance of the sun at sunrise and sunset is due to

Diameter of a plano-convex lens is $6 \,cm$ and thickness at the centre is 3 mm. If speed of light in material of lens is $2 \times 10^8$ m/s, the focal length of the lens is

The amplitude of a damped oscillator decreases to $0.9$ times its original magnitude is $5\, s$. In another $10\, s$ it will decrease to a times its original magnitude, where $\alpha$ equals

The image of an illuminated square is obtained on a screen with the help of a converging lens. The distance of the square from the lens is $40\, cm$. The area of the image is $9$ times that of the square. The focal length of the lens is :

Two blocks of masses $m$ and $M$ are connected by means of a metal wire of cross-sectional area $A$ passing over a frictionless fixed pulley as shown in the figure. The system is then released. If $M \,= \,2 m$, then the stress produced in the wire is:

A vessel contains a mixture of $1$ mole of oxygen and two moles of nitrogen at $300 \,K$. The ratio of the rotational kinetic energy per $ O_{2} $ molecule to that per $ N_{2} $ molecule is

A stone falls freely under gravity. It covers distances $h_1, \, h_2 $ and $h_3$ in the first 5 seconds, the next 5 seconds and the next 5 seconds respectively. The relation between $h_1 , \,h_2 $ and $h_3$ is

The amount of heat energy required to raise the temperature of 1 g of Helium at NTP, from $T_1K$ to $T_2K$ is

A rod PQ of mass M and length L is hinged at end P. The rod is kept horizontal by a massless string tied to point Q as shown in figure. When string is cut, the initial angular acceleration of the rod is

A certain mass of Hydrogen is changed to Helium by the process of fusion. The mass defect in fusion reaction is 0.02866 u. The energy liberated per u is (given 1 u=931 MeV)

A wave travelling in the +ve x-direction having displacement along y-direction as 1 m, wavelength 2π in and frequency of $\frac1{π}$Hz is represented by

If we study the vibration of a pipe open at both ends, then the following statement is not true

The upper half of an inclined plane of inclination θ is perfectly smooth while lower half is rough. A block starting from rest at the top of the plane will again come to rest at the bottom, if the coefficient of friction between the block and lower half of the plane is given by

The velocity of a projectile at the initial point A is (2i+3j) m/s. Its velocity (in m/s) at point B is

A gas is taken through the cycle A⇢B⇢C⇢A ,as shown. What is the net work done by the gas?

A piece of iron is heated in a flame. It first becomes dull red then becomes reddish yellow and finally turn to white hot. The correct explanation for the above observation is possible by using