List of top Physics Questions

If the Earth were to suddenly contract to $\frac{1}{n}$ th of its present radius without any change in its mass, the duration of the new day will be nearly

A plano-concave lens is made of glass of refractive index $1.5$ and the radius of curvature of its curved face is $100 \,cm$. What is the power of the lens?

An object weights $m_1$, in a liquid of density $d_1$ and that in liquid of density $d_2\,$ is $\, m_2.$ The density $d$ of the object is

An SHM is given by $y = 5 [\sin (3 \pi t) + \sqrt{3} \cos (3 \pi t)] $ What is the amplitude of the motion of $y$ in metre?

A circular disc is to be made by using iron and aluminium, so that it aquires momentum of inertia about its geometrical axis. It is possible with

A particle is moving with a constant speed $v$ in a circle. What is the magnitude of average velocity after half rotation ?

Four charges equal to $-Q$ are placed at the four corners of a square and a charge $q$ is at its centre. lf the system is in equilibrium, the value of $q$ is

A material has Poisson?s ratio $0.50$. If a uniform rod of it suffers a longitudinal strain of $2 ? 10^{-3}$, then the percentage change in volume is

Which of the following graphs represents the gravitational field intensity due to solid sphere of radius $ R $ ?

If a graph is plotted between $T^2$ and $r^3$ for a planet, then its slope will be (where $M_S$ is the mass of the sun)

Block A of mass 4 kg and block B of mass 6 kg are resting on a horizontal surface as shown in the figure. There is no friction between the block B and the horizontal surface. The coefficient of friction between the blocks is 0.2. If the value of $ g=10\,m/{{s}^{2}}, $ the maximum horizontal force F that can be applied on block B without any relative motion between A and B is

The excess pressure inside a soap bubble A is twice that in another soap bubble B. The ratio of volumes of A and B is

A closely wound solenoid $80 \,cm$ long has $5$ layers of winding of $400$ turns each. The diameter of the solenoid is $1.8\, cm$. If the current carried is $8.0\, A$, the magnitude of $B$ inside the solenoid near its centre will be

In the circuit shown, the currents $i_1$ and $i_2$ are

A $1.0\, m$ long metallic rod is rotated with an angular frequency of $400 \,rad /s$ about an axis normal to the rod passing through its one end. A constant and uniform magnetic field of $0.5\, T$ parallel to the axis exists everywhere. The emf developed across the ends of the rod is

A coil having 500 square loops of side 10 cm is placed normal to magnetic field which increases at a rate of 1 T s$^{-1}$. The induced e.m.f. is

Two positive charges of magnitude $'q'$ are placed at the ends of a side (side 1) of a square of side $'2a'$. Two negative charges of the same magnitude are kept at the other corners. Starting from rest, if a charge $Q$ moves from the middle of side $1$ to the centre of square, its kinetic energy at the centre of square is :

Two charges $4q$ and $q$ are placed $3x$ apart in air $A$ charge $Q$ is placed at a point on the line joining so that the systein of these charges remains in equilibrium. Then, the distance of $Q$ from $4q$ and the value of $Q$ are

The specific heat capacity of a metal at low temperature (T) is given as : $C_{p} \left(kjK^{-1} kg^{-1}\right) = 32 \left(\frac{T}{400}\right)^{3}$ A 100 gram vessel of this metal is to be cooled from $20^{\circ}K$ to $4^{\circ}K$ by a special refrigerator operating at room temperature $\left(27^{\circ}C\right)$. The amount of work required to cool the vessel is :

An unpolarized light is incident on a system of two crossed polaroids $A$ and $B$. Now the second polaroid $B$ is rotated by, $30^{\circ} $ towards $A$. Percentage of light transmitted through the system is

An aluminium sphere of 20 cm diameter is heated from 0$^{\circ}$C to 100$^{\circ}$C. Its volume changes by (given that coefficient of linear expansion for aluminium $\alpha_{AI} = 23 ? 10^{-6}/^{\circ}C)$

A thin circular disk of radius $R$ is uniformly charged with density $\sigma$ > 0 per unit area. The disk rotates about its axis with a uniform angular speed $\omega$. The magnetic moment of the disk is :

The masses of the three wires of copper are in the ratio 5 : 3 : 1 and their lengths are in the ratio 1 : 3 : 5. The ratio of their electrical resistances is