List of top Physics Questions asked in UP Board XII

The energy of a photon is 10 eV. Determine (i) the dynamic mass of the photon, (ii) the frequency of the photon.
(Given: \( h = 6.6\times10^{-34}\ \text{J s} \), \( c = 3\times10^{8}\ \text{m/s} \), \( 1\ \text{eV} = 1.6\times10^{-19}\ \text{J} \).)

Figure shows a rectangular loop being pulled out of a magnetic field \( B \) with a velocity \( v \) by applying an external force \( F \). Find the amount of magnetic force induced on the loop and show its direction.

A circular coil of radius 2.0 cm carries a current of 1.0 A. If the coil has 100 turns, find the intensity of magnetic field at the centre of the coil.

Discuss the working method of a half-wave rectifier using a p-n junction diode.

Draw (i – δ) curve for a triangular prism and show the angle of minimum deviation.

Find out equivalent energy of 1·0 gm of a substance.

Amplitude of intensity of magnetic field of an electromagnetic wave in vacuum is 500 nT. What will be the amplitude of the intensity of electric field of the wave?

Prove that the energy density inside a charged capacitor is \( \tfrac{1}{2}\varepsilon_0 E^2 \).

Energy of hydrogen atom in ground state is −13·6 eV. What will be the kinetic energy and the potential energy of the electron in the state?

In an AC circuit, if the current \(i = 2\sin\omega t\) ampere and the voltage \(V = 5\cos\omega t\) volt, then the power loss will be:

Write the unit of self-inductance.

A thin transparent sheet is placed in front of one slit of a Young's double slit. The fringe width will:

Find out the magnetic moment of a rectangular coil of size 20 cm × 10 cm having 10 A current.

The unit of \(\dfrac{1}{\mu_0 \varepsilon_0}\) is:

Two resistors \(R\) and \(2R\) are connected in parallel in an electric circuit. The thermal energies developed in \(R\) and \(2R\) are in the ratio:

The resistance of a wire is 16 ohms. By melting it, the wire is stretched to half of its original length. What will be the resistance of the new wire?

The difference in angular momentum of electron between two successive orbits of hydrogen atom is

By drawing ray-diagram, explain the formation of image by a compound microscope. Establish the formula for its magnifying power.
OR
What is meant by binding energy of nucleus? Draw the graph of binding energy per nucleon with respect to the mass number. Discuss fission and fusion reactions with the help of this curve.

How is the p-n junction diode used as a full wave rectifier? Explain its working process by making its simple circuit.
OR
What are de Broglie's matter-waves? The work function of potassium is \( 2\!\cdot\!0\ \text{eV} \). When ultraviolet light of wavelength \( 3500\ \text{\AA} \) falls on the surface of potassium, calculate the maximum kinetic energy of the emitted photoelectrons in electron-volt.

Explain Biot-Savart law. Deduce the formula for magnetic field produced due to a straight current carrying conductor.
OR
An α-particle, accelerated with the potential difference of V volt strikes with a nucleus (atomic number = Z). If r be the nearest distance of closest approach to the nucleus then prove that r = 14·4 Z/V Å.

Deduce the formula of equivalent capacity of three condensers connected in parallel.

Obtain the formula for the magnetic field inside a current carrying solenoid with the help of Ampere's circuital law.
OR
Obtain the formula for moment of couple acting on a magnetic dipole in a magnetic field. Define magnetic dipole moment with the help of this.

What do you mean by eddy current? How does it affect the energy losses? Write the uses of eddy current.