Class 12 PhysicsImportant Questions for Board Exams

State and prove Gauss's law. Apply it to find the electric field due to an infinitely long straight wire.

Derive an expression for the electric field on the equatorial line of an electric dipole.

Derive the expression for the energy stored in a parallel plate capacitor. What happens when a dielectric slab is inserted?

State Kirchhoff's laws. Using them, find the current in each branch of a given circuit.

Derive the condition for balance of a Wheatstone bridge.

State Biot-Savart law. Use it to find the magnetic field at the centre of a circular current loop.

Distinguish between diamagnetic, paramagnetic and ferromagnetic substances. Give one example of each.

State Faraday's laws of electromagnetic induction. Derive an expression for motional EMF.

Derive an expression for the impedance of a series LCR circuit. Define resonance and Q-factor.

An LCR circuit has L = 0.1H, C = 25μF, R = 10Ω. Find the resonant frequency.

What is displacement current? Why did Maxwell introduce it?

Describe the electromagnetic spectrum. Give one use of each type of radiation.

Draw a ray diagram for a compound microscope when the final image is at infinity. Derive the expression for magnifying power.

In Young's double slit experiment, derive the expression for fringe width. What happens to the fringe width if: (i) wavelength is increased (ii) slit separation is increased?

Explain the photoelectric effect. Write Einstein's photoelectric equation and explain each term.

Calculate the de Broglie wavelength of an electron accelerated through 100V.

State Bohr's postulates. Derive the expression for the radius of the nth orbit of hydrogen atom.

What is binding energy? Draw a binding energy per nucleon vs mass number graph and explain its features.

The half life of a radioactive isotope is 5 years. How much of 100g remains after 20 years?

Explain the working of a p-n junction diode as a full wave rectifier with a circuit diagram and waveform.

Draw the truth table for NAND and NOR gates. Why are they called universal gates?