List of top Physics Questions

A Carnot?s engine operates with source at $127?C$ and sink at $ 27?C$. If the source supplies 40 kJ of heat energy, the work done by the engine is
Two capillary tubes of radii 0.2 cm and 0.4 cm are dipped in the same liquid. The ratio of heights through which liquid will rise in the tubes is
A block of wood floats in water with $\left( \frac{4}{5} \right)^{th}$of its volume submerged. If the same block just floats in a liquid, the density of the liquid (in Kg m$^{-3}$) is
A wire suspended vertically from one of its ends is stretched by attaching a weight of 200 N to the lower end. The weight stretches the wire by 1 mm. Then the elastic energy stored in the wire is
From the top of a tower of height 40 m, a ball is projected upwards with a speed of ${20 \,m \, s^{-1}}$ at an angle of elevation of 30?. Then the ratio of the total time taken by the ball to hit the ground to its time to same height is Take ${g = 10 \, m \, s^{-2}}$
A boy walks to his school at a distance of 6 km with constant speed of ${2.5\, km \, h^{-1}}$ and walks back with a constant speed of ${4\, km \, h^{-1}}$. His average speed for round trip expressed in ${ km \, h^{-1}}$, is
Two bars $A$ and $B$ of circular cross-section and of same volume and made of the same material are subjected to tension. If the diameter of $A$ is half that of $B$ and if the force applied to both the rods is the same and it is in the elastic limit, the ratio of extension of $A$ to that of $B$ will be
A 280 day old radioactive substance shows an activity of 6000 dps, 140 days later its activity becomes 3000 dps. What was its initial activity?
X-rays, gamma rays and microwaves travelling in vacuum have
Two thin plano-convex lenses each of focal length $f$ are placed as shown in the figure. The ratio of their effective focal lengths in the three cases is
In the loop shown, the magnetic induction at the point $O$ is
A planet moving around sun sweeps area $A_1$ in $2$ days, $A_2$ in $3$ days and $A_3$ in $6$ days. Then the relation between $A_1, A_2 $ and $A_3$ is
When a mass is rotating in a plane about a fixed point, its angular momentum is directed along
If $v_e$ is escape velocity and $v _o$ is orbital velocity of a satellite for orbit close to the earth's suface, then these are related by
A car of mass m starts from rest and accelerates so that the instantaneous power delivered to the car has a constant magnitude $P_0$. The instantaneous velocity of this car is proportional to
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
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 cube has a side of length $1.2 \times 10^{-2} m$. Calculate its volume.
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 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 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 :
The force constant of a spring gun is $50 \,N / m$. If a ball of $20 \,g$ be shoot by the gun, so that its spring is compressed by $10 \,cm$, the velocity of the ball is:
Fast neutrons can easily be solved down by
The linear momentum $p$ of a body moving in one dimension varies with time $t$ according to the equation $p = a + bt^2$, where $a$ and $b$ are positive constant. The net force acting on the body is