# Class 12 Physics Imp Qn’s

**Mechanics**

**Important Questions of Mechanics is given as:**

### Unit 1: Rotational motion Important Topics and Question

Important Questions of Rotational Motion is given as:

#### Topics:

- Introduction of Rotational Dynamics
- Equations of Angular Motion and Linear Motion
- Relation between the moment of inertia and torque
- Radius of Gyration
- Moment of inertia of thin uniform rod rotating about its center and its one end
- Derivation of rotational kinetic energy
- What is torque? Relation between torque and angular acceleration of a rigid body
- Principle of conservation of angular momentum
- Solve Numerical problems and conceptual Questions regarding the rotational Dynamics (cover each topic)

### Unit 2: Periodic motion Important Topics and Questions

Important Questions of Periodic is given as:

#### Topics:

- Define SHM, its equation, and its expression for energy.
- Angular SHM and its periods
- Expression of the time period of a simple pendulum and damped oscillation.
- Numerical Problems from each Topic

### Unit 3: Fluid statics Important Topics and Questions

Important Questions of Fluid Statics is given as:

#### Topics:

- Explain Archimedes and Pascal’s law.
- Up-thrust, pressure in fluid, buoyancy, center of buoyancy, and metacenter
- Law of Floatation
- Surface Tension with its principle
- Angle of contact and capillarity
- Newton’s formula for the viscosity of the liquid
- Bernoulli’s equation and its application
- State and Explain Stoke’s Law and use it to find the Coefficient of viscosity of the given liquid
- Solve Numerical problems and conceptual Questions regarding the fluid statics

**Heat and Thermodynamics**

**Important Questions of Heat and Thermodynamics is given as:**

### Unit 4: First law of Thermodynamics Important Topics and Questions

Important Questions of 1st law of Thermodynamics is given as:

#### Topics:

- Concept of Thermodynamics
- Work done by System / on System
- Latent Heat and Internal Energy
- First Law of Thermodynamics / its limitations
- Cp-Cv = R ( Myer’s Relation )
- Work done during an adiabatic and isothermal process
- Prove : PV ^ (gamma) = constant
- PV diagram ( adiabatic, isothermal process, isobaric, isochoric )
- Reversible and irreversible process
- Numerical related to the first law of thermodynamics and thermodynamics process

### Unit 5: Second law of Thermodynamics Important Topics and Questions

Important Questions of 2nd law of thermodynamics is given as:

#### Topics:

- State Second law of thermodynamics ( Kelvin’s and Clausius’s Statement )
- Heat Engine and its efficiency
- Carnot’s Cycle with PV diagram and Calculate the work done of each step.
- Internal Combustion engines, Otto engines, diesel engine
- Refrigerator as heat engine working in the reverse direction
- Entropy and its role
- Mathematical problems related to Heat engines ( very important, efficiency types question)

**Wave and Optics**

### Unit 6: Wave motion Important Topics and Questions

#### Topics:

- Progressive wave
- Stationary waves
- Frequency, Amplitude, velocity, period, etc of a progressive wave

### Unit 7: Mechanical waves Important Topics and Questions

#### Topics:

- Speed of wave motion
- Velocity in solid, liquid, and gas
- Newton’s formula of the velocity of sound in gas
- Laplace correction
- Effect of temperature, pressure, and humidity on the velocity of sound
- Solve some numerical problems related to the velocity of sound in the given medium and condition.

### Unit 8: Waves in pipes and string Important Topics and Questions

#### Topics:

- Open and Closed organ pipes
- Harmonics and overtones
- End correction in pipes
- Formula of the velocity of transverse wave
- Vibration of String and overtones
- Know the laws of Vibration of fixed string.

### Unit 9: Acoustic phenomena Important Topics and Questions

#### Topics:

- Sound waves as pressure waves
- Characterize the sound using its intensity, loudness, quality, and pitch
- Doppler’s effect ( most important, numerical )

### Unit 10: Nature and propagation Important Topics and Questions

#### Topics:

- Huygens’s principle to explain the reflection and refraction of light

### Unit 11: Interference Important Topics and Questions

#### Topics:

- Phenomenon of Interferences
- Coherent source
- Young’s Double slit experiment and obtain nth order maxima ( most important )

### Unit 12: Diffraction Important Topics and Questions

#### Topics:

- Diffraction at a single slit
- Expression for nth Order
- Diffraction grating
- Resolving power of optical instruments
- Solve some numerical

### Unit 13: Polarization Important Topics and Questions

#### Topics:

- Phenomenon of polarization
- Brewster’s law and its use

**Important Questions of Wave and Optics is given as:**

- Define wave motion. Derive the progressive wave equations in a medium.
- Starting with the definition of stationary waves, prove that the distance between any two consecutive nodes or antinodes in a stationary wave is ƛ/2.
- Write an expression for Newton’s formula for the velocity of sound in air. Explain the necessary correction made by Laplace.
- Define end correction. Show that, in an open organ pipe, both odd and even harmonics can be produced.
- Define natural frequency. Describe an experiment to determine the velocity of sound in air by the resonance air column tube method.
- Describe a sound wave as a pressure wave and deduce an expression for the pressure amplitude.
- Define beats. Obtain an expression for the beat frequency produced by the superposition of two waves of slightly different frequencies.
- What is the Doppler effect in sound? Obtain an expression for the apparent frequency of sound when both source and observer are moving towards each other.
- State Huygen’s law and use it to verify Snell’s law.
- Define coherent sources of light. Describe Young’s double-slit experiment and show that the bright fringes and dark fringes are equally spaced.
- Define polarization of light. Show that, μ=tan𝜭p, where the symbols have their usual meanings.

**Electricity and Magnetism**

### Unit 14: Electric Circuits Important Topics and Questions

#### Topic:

- Kirchhoff’s Current law and Voltage law
- Wheatstone bridge
- AC working principle
- Combination of resistors ie. series and parallel
- Potentiometer and use of Potentiometer
- Meter Bridge
- Shunt / Galvanometer
- Conversion of galvanometer into ammeter or Voltmeter
- Joule’s law of heating
- Superconductor / perfect Conductor
- Some numerical related to the above topics

### Unit 15: Thermoelectric effects Important Topics and Questions

#### Topics:

- Seebeck effect and its application
- Thermocouple
- Peltier effect
- Thermopile
- Some Mathematical problems related to topics

### Unit 16: Magnetic field Important Topics and Questions

#### Topics:

- Concept of magnetic field lines and magnetic flux
- Oersted’s Experiment
- Force and Torque on the rectangular coil
- Moving coil galvanometer and its application
- Hall effect and hall Voltage law/hall prode
- Biot and Savart law and its application ( i. circular coil, ii. long straight conductor, iii. a long solenoid )
- Ampere’s law and its application ( i. long straight conductor, ii. Straight solenoid, iii. A toroidal solenoid )
- Force between two parallel conductors carrying current.
- Solve the basic numerical problems ( Only basic is enough)

### Unit 17: Magnetic properties of materials Topics and important Questions

#### Topics:

- Relative permeability and relative susceptibility
- Hysteresis of ferromagnetism
- Important: Di-, -para, and -ferromagnetic materials

### Unit 18: Electromagnetic Induction Important Topics and important Questions

#### Topics:

- Faraday’s laws
- Lenz’s law
- A.C. generators: Eddy currents
- Self-Induction and mutual induction
- Energy stored in an inductor
- Transformer

### Unit 19: Alternating Currents Important Questions and Topics

#### Topics:

- Peak and RMS value of AC current and voltage
- AC through a resistor, a capacitor, and an inductor
- Phasor Diagram
- Series circuits containing a combination of resistance, capacitance, and inductance
- Series resonance, Quality factor
- Power in AC circuits: power factor
- Numerical ( only easy because it’s not your relationship to be Complected )

**Important Questions of Electricity and Magnetism is given as:**

- How can you convert a galvanometer into an ammeter (or voltmeter)? Explain.
- Discuss the mechanism of metallic conduction. Derive a relation between current density and drift velocity.
- State and apply Kirchoff’s rule to measure the unknown resistance of a wire by using the Wheatstone bridge circuit.
- State the principle of meter bridge. Describe how it is used to determine the resistance of a wire.
- What is the principle of a potentiometer? Explain with necessary theory how you would determine the internal resistance of a cell using this principle.
- What do you mean by the thermoelectric effect? Discuss the variation of thermo emf in a thermocouple with the temperature change.
- State and explain Biot – Savart’s law. Use it to find the magnetic field due to a long straight current-carrying conductor.
- State Ampere’s law. Deduce an expression for the force between two parallel current-carrying wires.
- State Faraday’s law of electromagnetic induction. Derive an expression for the emf induced in a straight conductor moving at right angles to the direction of a uniform magnetic field.
- State Faraday’s law of electromagnetic induction. Deduce an expression for the emf induced in a coil rotating uniformly in a uniform magnetic field.
- Explain the principle and working of a transformer.
- Discuss the condition for the resonant frequency of the LCR alternating current circuit.

**Modern Physics**

### Unit 20: Electrons Important Question and Topics

#### Topics:

- Millikan’s oil drop experiment
- Motion of electron beam in electric and magnetic fields
- Thomson’s experiment to determine specific charge ( e/m )
- Related mathematical problems ( I will upload soon: click here )

### Unit 21: Photons Important Topics and Important Questions

#### Topics:

- Quantum nature of radiation
- Einstein’s photoelectric equation: stopping potential
- Measurement of Plank’s constant
- Some numerical ( I will upload: check later )

### Unit 22: Semiconductor devices Important Questions and Topics

#### Topics:

- P-N junction
- Forward bias and reverse bias
- Full wave rectification
- Logic gate: NOT, OR, AND, NAND, AND NOR

### Unit 23: Quantization of energy Important Questions and Topics

#### Topics:

- Bohr’s theory
- Spectral series: Excitation and ionization potentials
- Energy Level: Emission and absorption spectra
- De Broglie Theory: Duality
- Uncertainty principle
- X-rays: Nature and production
- Bragg’s law
- Numerical Concept Based

### Unit 24: Radioactivity and nuclear reaction Important Questions and Topics

#### Topics:

- Alpha, Beta particle, and Gamma ray
- Law of radioactive disintegration
- Half-life, mean-life, and decay constant
- Geiger-Muller tube
- Carbon dating
- Medical use of nuclear radiation
- Some numerical ( simple, but conceptual type )

### Unit 25: Recent trends in physics Important Questions and Topics

#### Topics:

- Seismology ( Surface and Internal waves, MCQ related )
- Gravitational wave
- Nanotechnology
- Higgs Boson

**Important Questions of Modern Physics is given as:**

- Describe the construction and working principle of Millikan’s oil-drop experiment to determine the charge of an electron.
- Define cross-field. Describe the construction and working principle of J.J. Thomson’s experiment to determine the specific charge of an electron.
- Define the threshold frequency and work function of a metal. Explain Einstein’s photoelectric equation.
- Describe the experiment to determine Planck’s constant.
- State Bohr’s postulates for the atomic model. Derive the expression for the radius of an electron bound to a hydrogen atom. (OR, to find the total energy of an electron in nth orbit.)
- Explain Bragg’s law of diffraction for X – rays.
- What is Zener’s breakdown? How can a Zener diode be used as a voltage regulator? Explain.
- Define mass defect. Explain the significance of the graph of binding energy per nucleon versus the atomic mass number.
- State the laws of radioactivity. Derive the relation between the half-life period and decay constant.

The topics listed above are Important Questions for the NEB exam in physics for the years 2023 / 2080. We also took some references to prepare for this content.

All the best for your exams.

For Model Questions Click Here.

**Class 12 Physics Based on the revised curriculum**

- Mechanics
- Heat and Thermodynamics
- Wave and Optics
- Electricity and Magnetism
- Modern Physics

### 1.Mechanics

- Introduction of Rotational Dynamics
- What is torque? Relation between torque and angular acceleration of a rigid body
- Solve Numerical problems and conceptual Questions regarding the rotational Dynamics (cover each topic)
- Define SHM, its equation, and its expression for energy.
- Expression of the time period of a simple pendulum and damped oscillation.
- Numerical Problems from each Topic of SHM
- Explain Archimedes and Pascal’s law.
- Up-thrust, pressure in fluid, buoyancy, center of buoyancy, and metacenter
- Surface Tension with its principle
- Bernoulli’s equation and its application
- State and Explain Stoke’s Law and use it to find the Coefficient of viscosity of the given liquid
- Solve Numerical problems and conceptual Questions regarding the fluid statics

### 2.Heat and Thermodynamics

- Concept of Thermodynamics
- First Law of Thermodynamics / its limitations
- Cp-Cv = R ( Myer’s Relation )
- PV diagram ( adiabatic, isothermal process, isobaric, isochoric )
- Reversible and irreversible process
- Numerical related to the first law of thermodynamics and thermodynamics process

### 3.Wave and Optics

- Frequency, Amplitude, velocity, period, etc of a progressive wave
- Laplace correction
- Open and Closed organ pipes Numericals
- Doppler’s effect ( most important, numerical )
- Huygens’s principle to explain the reflection and refraction of light
- Young’s Double slit experiment and obtain nth order maxima ( most important )
- Diffraction at a single slit
- Phenomenon of polarization & Brewster’s law and its use
- Define wave motion. Derive the progressive wave equations in a medium.
- Starting with the definition of stationary waves, prove that the distance between any two consecutive nodes or antinodes in a stationary wave is ƛ/2.
- Write an expression for Newton’s formula for the velocity of sound in air. Explain the necessary correction made by Laplace.
- Define end correction. Show that, in an open organ pipe, both odd and even harmonics can be produced.
- Define natural frequency. Describe an experiment to determine the velocity of sound in air by the resonance air column tube method.
- Describe a sound wave as a pressure wave and deduce an expression for the pressure amplitude.
- Define beats. Obtain an expression for the beat frequency produced by the superposition of two waves of slightly different frequencies.
- What is the Doppler effect in sound? Obtain an expression for the apparent frequency of sound when both source and observer are moving towards each other.
- State Huygen’s law and use it to verify Snell’s law.
- Define coherent sources of light. Describe Young’s double-slit experiment and show that the bright fringes and dark fringes are equally spaced.
- Define polarization of light. Show that, μ=tan𝜭p, where the symbols have their usual meanings.

### 4.Electricity and Magnetism

- How can you convert a galvanometer into an ammeter (or voltmeter)? Explain.
- Discuss the mechanism of metallic conduction. Derive a relation between current density and drift velocity.
- State and apply Kirchoff’s rule to measure the unknown resistance of a wire by using the Wheatstone bridge circuit.
- State the principle of meter bridge. Describe how it is used to determine the resistance of a wire.
- What is the principle of a potentiometer? Explain with necessary theory how you would determine the internal resistance of a cell using this principle.
- What do you mean by the thermoelectric effect? Discuss the variation of thermo emf in a thermocouple with the temperature change.
- State and explain Biot – Savart’s law. Use it to find the magnetic field due to a long straight current-carrying conductor.
- State Ampere’s law. Deduce an expression for the force between two parallel current-carrying wires.
- State Faraday’s law of electromagnetic induction. Derive an expression for the emf induced in a straight conductor moving at right angles to the direction of a uniform magnetic field.
- State Faraday’s law of electromagnetic induction. Deduce an expression for the emf induced in a coil rotating uniformly in a uniform magnetic field.
- Explain the principle and working of a transformer.
- Discuss the condition for the resonant frequency of the LCR alternating current circuit.

### 5.Modern Physics

- Millikan Oil Drop experiment
- Thomson’s experiment to calculate specific charge of an electron
- Einstein’s Photoelectric equation
- Bohr’s postulates and find the energy of electron of nth orbit
- Radius of nth Bohr’s orbit
- Gaseous discharge
- Full Wave Rectifier
- Describe the construction and working principle of Millikan’s oil-drop experiment to determine the charge of an electron.
- Define cross-field. Describe the construction and working principle of J.J. Thomson’s experiment to determine the specific charge of an electron.
- Define the threshold frequency and work function of a metal. Explain Einstein’s photoelectric equation.
- Describe the experiment to determine Planck’s constant.
- State Bohr’s postulates for the atomic model. Derive the expression for the radius of an electron bound to a hydrogen atom. (OR, to find the total energy of an electron in nth orbit.)
- Explain Bragg’s law of diffraction for X – rays.
- What is Zener’s breakdown? How can a Zener diode be used as a voltage regulator? Explain.
- Define mass defect. Explain the significance of the graph of binding energy per nucleon versus the atomic mass number.
- State the laws of radioactivity. Derive the relation between the half-life period and decay constant.