List of top Physics Questions

A ray of light is travelling through a rectangular glass slab (refractive index \(\frac{3}{2}\)) and is incident on the horizontal glass-air surface at the critical angle for the two media. The slab is then brought in contact with water (refractive index \(\frac{4}{3}\)) such that a thin horizontal layer of water is formed on the surface of the slab. Find the angle at which the ray will emerge into air from the water-air surface.

A circular coil of 100 turns and radius \( \left(\frac{10}{\sqrt{\pi}}\right) \, \text{cm}\) carrying current of \( 5.0 \, \text{A} \) is suspended vertically in a uniform horizontal magnetic field of \( 2.0 \, \text{T} \). The field makes an angle \( 30^\circ \) with the normal to the coil. Calculate:
the magnetic dipole moment of the coil, and
the magnitude of the counter torque that must be applied to prevent the coil from turning.

Three charges \(+20\,\mu C\), \(+20\,\mu C\) and \(-20\,\mu C\) are placed at the vertices \(A\), \(B\) and \(C\) respectively of an equilateral triangle of side \(1\,m\). Find the net force acting on the charge at vertex \(A\).

A thin charged spherical shell of radius \(10\,cm\) has a uniform surface charge density of \(20\,pC/cm^{2}\). The electric potential at a point \(8\,cm\) from the centre of the shell is:

A small ball is tied to a light inextensible thread of length \(64\,cm\) and is whirled in a vertical circle. If the thread is just taut at the highest point of the circle, then the minimum speed of the ball at the lowest point is: (Take \(g=10\,m/s^{2}\))

A spring of force constant \(K=1000\,N/m\) is compressed by \(5\,cm\). If a mass of \(2.5\,kg\) is attached and released, find its speed as it passes the equilibrium position.

Two large, thin, parallel sheets have surface charge densities of opposite signs and equal magnitude \(\sigma\). What is the magnitude of the electric field \((E)\) in the region between the sheets?

The temperature of \(2\) moles of a monoatomic gas changes from \(25^{\circ}C\) to \(35^{\circ}C\) in an adiabatic process. Find the work done.

A sphere encloses charges \(+5\,C\) and \(-2\,C\), while a charge \(-3\,C\) is outside the sphere. What is the electric flux through the sphere?

If the work function of a metal is \(1.2\,eV\) and the stopping potential is \(1.8\,V\), find the frequency of incident light on the metal surface.

Which of the following statements is correct during the formation of a PN junction?

A current of \(50\,mA\) flows through a loop of area \(10\,cm^{2}\) placed in a magnetic field of \(0.1\,T\). The angle between the magnetic field and the loop is \(60^{\circ}\). Find the torque acting on the loop.

A \(1\,\mu F\) capacitor is charged to \(12\,V\) and then connected to an identical uncharged capacitor. What will be the common potential?

\(L=50\,mH,\; C=100\,\mu F,\; R=50\,\Omega\). What does this circuit represent? (Assume \(\omega=200\,rad/s\))

Two parallel wires carry equal currents of \(2\,A\) in opposite directions. If the length of each wire is \(0.5\,m\) and the distance between them is \(10\,cm\), then find the force between them.

The electron mobility in a conductor is \(32~\text{cm}^{2}/\text{Vs}\). What is the relaxation time of free electrons? (Given: \(e=1.6\times10^{-19}~C,\; m=9.1\times10^{-31}~kg\))

The area of an airplane wing is \(A=4\,m^{2}\). Air flows with velocity \(v_{1}=80\,m/s\) above the wing and \(v_{2}=60\,m/s\) below it. The density of air is \(1.2\,kg/m^{3}\). Find the pressure difference \((\Delta P)\) between the upper and lower surfaces of the wing.

A thin prism has an angle of \(8^{\circ}\) and a minimum deviation of \(6^{\circ}\). Find the speed of light in the prism.

A car moves at a speed of \(600\,\text{km/h}\) on a frictionless banked road with \(\theta=30^{\circ}\). Take \(g=10\,\text{m/s}^{2}\). Find the radius of the road.

An ideal gas is made of polyatomic molecules. Each molecule has three translational, three rotational and \(f\) number of vibrational modes. If the ratio of heat capacities \[ \frac{C_P}{C_V}=\frac{8}{7} \] then the value of \(f\) is:

The measured length of a rod is (20.0 $\pm$ 0.2) cm. The percentage error in the measurement is:

A coil of 100 turns experiences a change in magnetic flux from 0.05 Wb to 0.01 Wb in 0.2 s. The induced emf is:

The resistance of a semiconductor decreases when its temperature increases because: