This article contains all the important theoretical questions for Physics – Class 12 CBSE Board Exam. The questions has been distributed chapter-wise. Set of these 10-15 questions per chapter will ensure more than 60% marks in Board Exam.

**Electrostatics**

- Derive an expression for the electric field at a point on the axial position of an electric dipole.
- Derive an expression for the electric field at a point on the equatorial position of an electric dipole.
- Describe the Principle, construction and working of Van de Graff generator.
- Derive an expression for the energy stored in a capacitor. Show that whenever two conductors share charges by bringing them into electrical contact, there is a loss of energy.
- Derive an expression for the effective capacitance when capacitors are connected in (a) series and (b) parallel
- Explain the principle of a capacitor and derive an expression for the capacitance of a parallel plate capacitor.
- State Gauss theorem and apply it to find the electric field at a point due to (a) a line of charge (b) A plane sheet of charge (c) A Charged spherical conducting shell

**Click Here for Important Questions for Class XII Board Exam – Physics – II** - State Coulomb’s law and express it in vector form. Derive it using Gauss theorem.
- Derive an expression for the torque on an electric dipole in a uniform electric field.
- Derive an expression for the work done in rotating an electric dipole in a uniform electric field
- Derive an expression for the energy stored (Potential Energy) in a dipole in a uniform electric field.
- Derive an expression for the electrostatic potential energy of a system of point charges
- Derive an expression for the capacitance of a parallel plate capacitor with (a) a dielectric slab (b) a metallic plate in between the plates of the capacitor.
- Define electric potential at a point. Derive an expression for the electric potential at a point due to (a) a point charge (b) a system of point charges (c) a dipole.
- Show that the work done in an electric field is independent of path.
- What are dielectrics? Distinguish polar and nonpolar dielectrics. Define the term Polarization vector.

#### Current Electricity

- Define drift velocity and derive an expression for it.
- Derive the expression I=nAevd
- Deduce Ohm’s law from elementary ideas and hence write an expression for resistance and resistivity.
- Derive an expression for conductivity in terms of mobility
- Explain the color coding of carbon resistors.
- Derive an expression for the current in a circuit with external resistance R when (a) n identical cells of emf E and internal resistance r are connected in series (b) m identical cells are connected in parallel
- State and explain Kirchhoff’s laws.

##### **Click Here for Important Questions for Class XII Board Exam – Physics – II**

- State and explain the principle of Wheat Stone’s principle. Deduce it using Kirchhoff’s laws.
- Describe how you will determine the resistance of a given wire using Meter Bridge.
- Explain the principle of a potentiometer. Describe how will you determine (a) the ratio of emfs of two primary cells using potentiometer. (b) The internal resistance of a primary cell using potentiometer.
- Explain the variation of resistance and resistivity with temperature and hence define temperature coefficient of resistance and resistivity.Click Here to see chapter-wise notes for Class 12 Board Exams of Physics.

#### Magnetic Effect of Current

- State Biot- Savart law and apply it to find the magnetic field due to a circular loop carrying current at a point (a) at its centre (b) on the axis
- State Ampere’s circuital law and apply it to find the magnetic field (a) inside a current carrying solenoid (b) inside a current carrying toroid
- Apply Ampere’s circuital law to determine the magnetic field at a point due to a long straight current carrying conductor.
- Derive an expression for the force on a current carrying conductor in a uniform magnetic field
- Derive an expression for the force between long straight conductors carrying current and hence define 1 ampere.
- Derive an expression for the torque on a current carrying loop in a uniform magnetic field.
- Describe the principle construction and working of a Moving coil galvanometer.
- Describe the conversion of a moving coil galvanometer into (a) Ammeter (b) Voltmeter
- What is radial magnetic field? What is its importance in a moving coil galvanometer? How is a radial magnetic field realized in moving coil galvanometers?
- Describe the principle construction and working of a cyclotron. Explain why an electron cannot be accelerated using a cyclotron.
- Describe the motion of a charged particle in a magnetic field when it enters the field (a) perpendicular to the field lines (b) obliquely making and angle Θ with the field lines
- Derive an expression for the magnetic dipole moment of a revolving electron and hence define Bohr magneton.

#### Electromagnetic Induction (EMI)

- State and Explain Faraday’s laws of electromagnetic induction.
- State Lenz’ Law and show that it is in accordance with the law of conservation of energy.
- Use Lenz’ law to find the direction of induced emf in a coil when (a) a north pole is brought towards the coil (b) north pole taken away from the coil (c) A south pole is brought towards the coil and (d) a south pole is taken away from the coil, Draw illustrations in each case.

##### **Click Here for Important Questions for Class XII Board Exam – Physics – II**

- What is motional emf. Deduce an expression for it. State Fleming’s right hand rule to find the direction of induced emf.
- What are eddy currents? Describe the applications of eddy currents.
- Explain the working of (a) Electromagnetic Brakes (b) Induction Furnace
- Which physical quantity is called the INERTIA OF ELECTRICITY? Why is its called so?
- Define self induction and self inductance. What is its unit? Write its dimensions.
- Derive an expression for the self inductance of a long solenoid.
- Explain the phenomenon of mutual induction and define mutual inductance. Write the unit and dimensions of mutual inductance.
- What are the factors affecting mutual inductance of a pair of coils? Define coefficient of coupling.
- Describe the various methods of producing induced emf. Derive an expression for the instantaneous emf induced in a coil rotated in a magnetic field.
- What is displacement current? Explain its need.Click Here to see chapter-wise notes for Class 12 Board Exams of Biology

#### Alternative Current

- Describe the principle construction and working of an AC generator. Draw neat labeled diagram
- Define mean value of AC(over a half cycle) and derive an expression for it.
- Define RMS value of AC and derive an expression for it.
- Show that the average value of AC over a complete cycle is zero.
- Show that the current and voltage are in phase in an ac circuit containing resistance only.
- Deduce the phase relationship between current and voltage in an ac circuit containing inductor only.
- Deduce the phase relationship between current and voltage in an ac circuit containing capacitor only.
- Draw the phasor diagram showing voltage and current in LCR series circuit and derive an expression for the impedance
- What do you mean by resonance in Series LCR circuit? Derive an expression for the frequency of resonance in LCR circuit.
- Distinguish between resistance, reactance and impedance.
- Define quality factor (Q factor) of resonance and derive an expression for it.
- Describe the mechanism of electromagnetic oscillations in LC circuit and write expression for the frequency of oscillations produced.
- Derive an expression for the average power in an ac circuit.
- Define power factor. Deduce expression for it and explain wattless current?
- Describe the principle construction theory and working of a transformer.
- Describe the various losses in a transformer and explain how the losses can be minimized.

#### Electromagnetic Waves

- Explain the inadequacy of Ampere’s circuital law
- Describe Hertz experiment to demonstrate the production of electromagnetic waves
- Write the properties of electromagnetic waves.
- Write any five electromagnetic waves in the order of decreasing frequency and write any two properties and uses of each
- Deduce an expression for velocity of em waves in vacuum
- Establish the transverse nature of electromagnetic waves.
- Compare the properties of electromagnetic waves and mechanical waves

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