The following is a list of Class 12 Most Important Physics Questions for the NEB Exam in 2023 [2079 and 2080 B.S.].

Subject | Physics |
---|---|

Class | 12 ( NEB ) |

Chapter | 25 |

Total Marks | 75 marks |

Exam time | 3 hours |

Difficult portion | Electricity and magnetism |

Difficulty level | Medium |

Most Important Questions and Topics of Physics for the NEB exam |

## 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

#### 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

#### 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.

**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.

Also Check: Chemistry Most Important Question Class 12 NEB:

**Q: Which chapter is most important in physics class 12?**

A: According to the physics teacher, the Electron, Proton, and Modern Physics section is the most significant for getting excellent grades in class 12.

**Q: Which book is best for 12 physics?**

A: According to our source, the best books for Class 12 NEB are those that have MCQs, short questions, and numerical problems.

**Q: Is 12th physics difficult?**

A: The response differs from person to person. Some students find it difficult, while others find it simple; nonetheless, for the ordinary student who follows their teacher, watches YouTube videos, and works hard, it is simple.

**Q: How can I get A+ in NEB exam?**

Not to worry! Regularly study for 4-5 months and visit iswori.com.np for notes and important questions. You may easily obtain excellent marks in the NEB test if you use notes and other study resources.

**Q: Which Chapter is easy scoring in Physics in Nepal?**

A: You can do well in the NEB exam if you focus on the subject when the teacher is teaching. Any chapter is easy if u spend enough time.