List of top Physics Questions

A 200 g sample of water at 80°C is mixed with 100 g of water at 20°C. Assuming no heat loss to the surroundings, what is the final temperature of the mixture?
A double convex lens of glass has both faces of the same radius of curvature 17 cm. Find its focal length if it is immersed in water. The refractive indices of glass and water are 1.5 and 1.33 respectively.
A car of mass 800 kg is moving in a circular path with a radius of 50 m at a speed of 20 m/s. Calculate the centripetal force acting on the car.
A car of mass 1000 kg is moving with a velocity of 20 m/s. The driver applies the brakes, and the car comes to rest in 10 seconds. Find the average force exerted by the brakes to stop the car.
A cylindrical pipe has a radius of \( 0.1 \, \text{m} \). If the speed of water flowing through the pipe is \( 2 \, \text{m/s} \), calculate the volume flow rate of water through the pipe.
A concave mirror has a focal length of \( 10 \, \text{cm} \). An object is placed at a distance of \( 15 \, \text{cm} \) from the mirror. Calculate the position of the image formed.
In a certain camera, a combination of four similar thin convex lenses are arranged axially in contact. Then the power of the combination and the total magnification in comparison to one lens will be, respectively:

AB is a part of an electrical circuit (see figure). The potential difference \(V_A - V_B\), at the instant when current \(i = 2\) A and is increasing at a rate of 1 amp/second is:

A ball of mass 0.5 kg is dropped from a height of 10 m. The ball hits the ground and rises to a height of 1.5 m. The impulse imparted to the ball during its collision with the ground is : (Take \(g = 9.8 \, \text{m/s}^2\))
The electric field in a plane electromagnetic wave is given by \(E_z = 60 \cos(5x + 1.5 \times 10^{10} t)\) V/m. Then expression for the corresponding magnetic field (\(B_y\)) is (here subscripts denote the direction of the field) is:

The current passing through the battery in the given circuit, is: 

An electron (mass \(9 \times 10^{-31}\) kg and charge \(1.6 \times 10^{-19}\) C) moving with speed \(c/100\) (\(c\) = speed of light) is injected into a magnetic field of magnitude \(9 \times 10^{-4}\) T perpendicular to its direction of motion. We wish to apply a uniform electric field \( \vec{E} \) together with the magnetic field so that the electron does not deflect from its path. (speed of light \(c = 3 \times 10^8\) m/s):
Define electric flux through a surface. Give the significance of a Gaussian surface. A charge outside a Gaussian surface does not contribute to total electric flux through the surface. Why?
A gas in a cylinder is compressed from an initial volume of \( 5 \, \text{m}^3 \) to a final volume of \( 2 \, \text{m}^3 \) while maintaining a constant pressure of \( 1 \times 10^5 \, \text{Pa} \). Calculate the work done by the gas during the compression.
A charge \( Q \) is fixed in position. Another charge \( q \) is brought near charge \( Q \) and released from rest. Which of the following graphs is the correct representation of the acceleration of the charge \( q \) as a function of its distance \( r \) from charge \( Q \)?
A battery of emf \( E \) and internal resistance \( r \) is connected to a rheostat. When a current of 2A is drawn from the battery, the potential difference across the rheostat is 5V. The potential difference becomes 4V when a current of 4A is drawn from the battery. Calculate the value of \( E \) and \( r \).
In the circuit, three ideal cells of e.m.f. \( V \), \( V \), and \( 2V \) are connected to a resistor of resistance \( R \), a capacitor of capacitance \( C \), and another resistor of resistance \( 2R \) as shown in the figure. In the steady state, find (i) the potential difference between P and Q, (ii) the potential difference across capacitor C.
potential difference across capacitor C

The output (Y) of the given logic implementation is similar to the output of an/a  …………. gate.

Two convex lenses A and B, each of focal length 10.0 cm, are mounted on an optical bench at 50.0 cm and 70.0 cm respectively. An object is mounted at 20.0 cm. Find the nature and position of the final image formed by the combination.

Show the refraction of light wave at a plane interface using Huygens' principle and prove Snell's law.

Two point charges \( q_1 \) and \( q_2 \) are placed at a distance \( r \) in vacuum. The force between them is \( F \). If the distance is doubled and both charges are halved, what will be the new force?

You are given a dipole of charge \( +q \) and \( -q \) separated by a distance \( 2l \). A sphere 'A' of radius \( R \) passes through the centre of the dipole as shown below and another sphere 'B' of radius \( 2R \) passes through the charge \( +q \). Then the electric flux through the sphere A is 

Two wires of the same material and the same radius have their lengths in the ratio 2:3. They are connected in parallel to a battery which supplies a current of 15 A. Find the current through the wires.
Figure shows variation of Coulomb force (F) acting between two point charges with \( \frac{1}{r^2} \), \( r \) being the separation between the two charges \( (q_1, q_2) \) and \( (q_2, q_3) \). If \( q_2 \) is positive and least in magnitude, then the magnitudes of \( q_1, q_2 \), and \( q_3 \) are such that:
variation of Coulomb force
Let \( \lambda_e \), \( \lambda_p \), and \( \lambda_d \) be the wavelengths associated with an electron, a proton, and a deuteron, all moving with the same speed. Then the correct relation between them is: