List of top Physics Questions

A convex lens of focal length 20 cm made of glass of refractive index 1.5 is immersed in water having refractive index 1.33. The change in the focal length of lens is

The two slits are 1 mm apart from each other and illuminated with a light of wavelength $5 \times 10^{-7}$ m. If the distance of the screen is 1 m from the slits, then the distance between third dark fringe and fifth bright fringe is

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

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

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 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 ${g = 10 \, m \, s^{-2}}$

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 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

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

A galvanometer having a resistance of 8 $\Omega$ is shunted by a wire of resistance 2 $\Omega$. If the total current is 1 A, the part of it passing through the shunt will be

Moment of inertia does not depend on

The instantaneous angular position of a point on a rotating wheel is given by the equation $\theta(t)=2t^3-6t^2$ The torque on the wheel becomes zero at

The velocity of efflux of a liquid through an orific in the bottom of the tank does not depend upon

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

An electron is accelerated under a potential difference of 182 V. The maximum velocity of electron will be (Charge of electron is $1.6 \times 10^{-19}C $ and its mass is $9.1 \times 10^{-31}kg) $

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:

If density of earth increases $4$ times and its radius becomes half of what it is, our weight will