List of top Physics Questions

A light meter measures the intensity \( I \) of the light falling on it. Theory suggests that this varies as the inverse square of the distance \( d \). Which graph of the results supports this theory?

Kepler's third law states that the square of period of revolution (T) of a planet around the sun, is proportional to third power of average distance, r between the sun and the planet i.e. $T^2 = Kr^3$.
Here, K is constant.
If masses of the sun and the planet are M and m respectively, then as per Newton's law of gravitation, force of attraction between them is $F = \frac{GMm}{r^2}$, where G is gravitational constant.
The relation between G and K is described as

A proton and an electron are placed in a uniform electric field. Which of the following is correct?

Two spherical conductors A and B of radii 1mm and 2mm are separated by a distance of 5 cm and are uniformly charged. If the spheres are connected by a conducting wire, then at equilibrium condition, the ratio of the magnitude of the electric fields at the surface of spheres A and B is

A (+)vely charged particle is placed near an infinitely long straight conductor where there is zero gravity. Then

For a gas $\frac{R}{C_{v}} = 0.4$, where ?$R$? is the universal gas constant and ?$C_v$? is molar specific heat at constant volume. The gas is made up of molecules which are

Two identical charged spheres suspended from a common point by two massless strings of lengths $l$, are initially at a distance $d(d < < l)$ apart because of their mutual repulsion. The charges begin to leak from both the spheres at a constant rate. As a result, the spheres approach each other with a velocity $v$. Then $v$ varies as a function of the distance $x$ between the spheres, as:

A source of sound $S$ emitting waves of frequency $100\, Hz$ and an observor $O$ are located at some distance from each other. The source is moving with a speed of $19.4\, m s^{-1}$ at an angle of $60^{\circ}$ with the source observer line as shown in the figure. The observor is at rest. The apparent frequency observed by the observer is (velocity of sound in air $330\, ms ^{-1}$ )

A capillary tube of radius $r$ is immersed vertically in a liquid such that liquid rises in it to height $h$ (less than the length of the tube). Mass of liquid in the capillary tube is $m$. If radius of the capillary tube is increased by $50 \%$, then mass of liquid that will rise in the tube, is

A resistor of resistance $R$, capacitor of capacitance $C$ and inductor of inductance $L$ are connected in parallel to $A C$ power source of voltage $\epsilon_{0} \sin \omega_{t}$. The maximum current through the resistance is half of the maximum current through the power source. Then value of $R$ is

A string of length $\ell$ is fixed at both ends. It is vibrating in its $3^{rd}$ overtone with maximum amplitude '$a$'. The amplitude at a distance $\ell /3$ from one end is.

A ray of light of intensity $I$ is incident on a parallel glass slab at point $A$ as shown in diagram. It undergoes partial reflection and refraction. At each reflection, $25 \%$ of incident energy is reflected. The rays $A B$ and $A^{\prime} B^{\prime}$ undergo interference. The ratio of $I_{\max }$ and $I_{\min }$ is :

Kepler's third law states that square of period of revolution $(T)$ of a planet around the sun, is proportional to third power of average distance $r$ between sun and planet i.e. $T^{2}=K r^{3}$ here $K$ is constant. If the masses of sun and planet are $M$ and $m$ respectively then as per Newton's law of gravitation force of attraction between them is $F=\frac{G M m}{r^{2}}$ here $G$ is gravitational constant. The relation between $G$ and $K$ is described as

Two spheres of different materials one with double the radius and one-fourth wall thickness of the other are filled with ice. If the time taken for complete melting of ice in the larger sphere is $25$ minute and for smaller one is $16$ minute, the ratio of thermal conductivities of the materials of larger spheres to that of smaller sphere is

Block $A$ of mass $m$ and block $B$ of mass $2 m$ are placed on a fixed triangular wedge by means of a massless, inextensible string and a frictionless pulley as shown in figure. The wedge is inclined at $45^{\circ}$ to the horizontal on both the sides. If the coefficient of friction between the block $A$ and the wedge is $2 / 3$ and that between the block $B$ and the wedge is $1 / 3$ and both the blocks $A$ and $B$ are released from rest, the acceleration of $A$ will be

Two wires are made of the same material and have the same volume. However wire $1$ has cross sectional area A and wire $2$ has cross-sectional area $3A$. If the length of wire $1$ increases by $\Delta x$ on applying force $F$, how much force is needed to stretch wire $2$ by the same amount?

For the angle of minimum deviation of a prism to be equal to its refracting angle, the prism must be made of a material whose refractive index :

Find the number of photon emitted per second by a $25$ watt source of monochromatic light of wavelength $ 6600\, ??. What is the photoelectric current assuming $3\%$ efficiency for photoelectric effect ?

The approximate depth of an ocean is $2700\, m$. The compressibility of water is $45.4 \times 10^{-11} Pa ^{-1}$ and density of water is $10^{3} kg / m 3 .$ What fractional compression of water will be obtained at the bottom of the ocean?

A deuteron of kinetic energy $50 \,keV$ is describing a circular orbit of radius $0.5$ metre in a plane perpendicular to the magnetic field $B$. The kinetic energy of the proton that describes a circular orbit of radius $0.5$ metre in the same plane with the same $B$ is

A frictionless wire $A B$ is fixed on a sphere of radius $R$. A very small spherical ball slips on this wire. The time taken by this ball to slip from $A$ to $B$ is

Two point dipoles $p \hat{k}$ and $\frac{p}{2} \hat{k}$ are located at $(0,0,0)$ and $(1\, m , 0,2\, m )$ respectively. The resultant electric field due to the two dipoles at the point $(1 \,m , 0,0)$ is