Important Definitions & Formulas

Class XI Physics | Board Exam Special

1. Units and Measurements

  • 1.
    Define Measurement. What is a Unit? List the essential characteristics of a standard unit.
  • 2.
    Differentiate between Fundamental (Base) Quantities and Derived Quantities. Give the SI Unit and Dimensional Formula for two examples of each.
  • 3.
    What is a System of Units? List the 7 Fundamental Units and 2 Supplementary Units in the SI system with their symbols.
  • 4.
    Define the following Practical Units of Length and write their values in meters:
    a) Astronomical Unit (AU)
    b) Light Year (ly)
    c) Parallactic Second (Parsec)
  • 5.
    Define the following Units of Time:
    a) Solar Day & Solar Year
    b) Lunar Month
    c) Shake (Write its value in seconds)
  • 6.
    Distinguish between Accuracy and Precision in measurement with a suitable example.
  • 7.
    Define Error in Measurement. Explain the causes and methods to minimize the following types of errors:
    a) Systematic Error
    b) Gross Error
    c) Least Count Error

2. Motion in a Straight Line

  • 8.
    Define Rest and Motion. Explain the concept of Frame of Reference.
  • 9.
    Define Path Length (Distance) and Displacement. Write their SI Units and Dimensional Formulas. Distinguish between them.
  • 10.
    Define Uniform Motion and Non-Uniform Motion. Give one example of each.
  • 11.
    Define Average Velocity and Average Speed. Write their mathematical formulas, SI Units, and Dimensional Formulas.
  • 12.
    Define Instantaneous Velocity. Write its mathematical formula using limits.
  • 13.
    Define Acceleration. Write its formula, SI Unit, and Dimensional Formula. Distinguish between Average Acceleration and Instantaneous Acceleration.
  • 14.
    Write the three Kinematic Equations for uniformly accelerated motion. Under what condition are these equations valid?
  • 15.
    What is Free Fall? Write the equations of motion for a freely falling body under gravity (assuming \( u=0 \)).

3. Motion in a Plane

  • 16.
    Define Scalar Quantity and Vector Quantity. Give two examples of each along with their SI units.
  • 17.
    Define Position Vector and Displacement Vector. Write their mathematical expressions.
  • 18.
    Define the following types of vectors:
    a) Equal Vector, Negative Vector
    b) Parallel Vectors, Anti-Parallel Vectors
    c) Collinear Vector, Co-initial Vector
    d) Coplanar Vector, Orthogonal Vector
    e) Zero (Null) Vector
  • 19.
    Define Unit Vector. Write its formula, notation, and significance. What is the unit vector of \( \vec{A} \)?
  • 20.
    State the Triangle Law, Parallelogram Law, and Polygon Law of vector addition.
  • 21.
    What is meant by the Resolution of a Vector? Write the expressions for rectangular components (\(A_x, A_y\)) of a vector in a plane.
  • 22.
    Define Scalar Product (Dot Product). Write its formula. Is the result a scalar or vector?
  • 23.
    Define Vector Product (Cross Product). Write its formula. How is the direction of the resultant vector determined?
  • 24.
    Define Projectile Motion. Write the equation of the Trajectory of a Projectile.
  • 25.
    Write the formulas for the following in Projectile Motion:
    a) Time of Flight (T)
    b) Horizontal Range (R)
    c) Maximum Height (H)
  • 26.
    Define Uniform Circular Motion. Is it an accelerated motion?
  • 27.
    Define the following Angular Quantities. Write their SI Units and Dimensional Formulas:
    a) Angular Displacement (\( \theta \))
    b) Angular Velocity (\( \omega \))
    c) Angular Acceleration (\( \alpha \))
  • 28.
    Define Centripetal Acceleration. Write its formula in terms of linear velocity (\(v\)) and angular velocity (\( \omega \)). Write its SI unit and dimensional formula.
  • 29.
    Distinguish between Centripetal Force and Centrifugal Force. Write the formula for Centripetal Force.

4. Laws of Motion

  • 30.
    Define Inertia. Explain the following with examples:
    a) Inertia of Rest
    b) Inertia of Motion
    c) Inertia of Direction
  • 31.
    State Newton's First Law of Motion (Galileo's Law of Inertia).
  • 32.
    Define Linear Momentum. Write its formula, SI Unit, and Dimensional Formula. Is it a scalar or vector quantity?
  • 33.
    State Newton's Second Law of Motion. Write the mathematical relation between Force, Mass, and Acceleration.
  • 34.
    Define Impulse. Write its formula, SI Unit, and Dimensional Formula. State the Impulse-Momentum Theorem.
  • 35.
    State the Law of Conservation of Linear Momentum. Write the mathematical condition for it.
  • 36.
    State Newton's Third Law of Motion. What are the essential conditions for forces to form an Action-Reaction pair?
  • 37.
    Distinguish between Inertial Frames and Non-Inertial Frames of Reference with examples.
  • 38.
    What is Normal Reaction (Normal Force)? Why is it always perpendicular to the contact surface?
  • 39.
    Define Friction. Explain the following types with their definitions:
    a) Static Friction
    b) Limiting Friction
    c) Kinetic Friction
    d) Rolling Friction
  • 40.
    Define Angle of Friction and Angle of Repose. Write the relation between them.
  • 41.
    What is meant by Banking of Roads? Why is it necessary? Write the formula for the maximum safe velocity on a banked road.
  • 42.
    What is a Pseudo Force? Under what condition does it act?

5. Work, Energy and Power

  • 43.
    Define Work Done. Write its dot product formula, SI Unit, and Dimensional Formula. Is it a scalar or vector quantity?
  • 44.
    Explain the conditions under which Work Done is:
    a) Positive
    b) Negative
    c) Zero (Give examples for each)
  • 45.
    Define Energy. Explain Kinetic Energy and Potential Energy. Write their formulas, SI Units, and Dimensional Formulas.
  • 46.
    State the Work-Energy Theorem. Write its mathematical equation.
  • 47.
    Distinguish between Conservative Forces and Non-Conservative Forces. Give two examples of each.
  • 48.
    State the Law of Conservation of Mechanical Energy. Write the mathematical condition for it.
  • 49.
    State the general Law of Conservation of Energy.
  • 50.
    Define Power. Write its formula, SI Unit, and Dimensional Formula. Define 1 Horse Power (HP) and its relation to Watt.
  • 51.
    Define Collision. Explain the following types based on direction:
    a) Head-on Collision (1D)
    b) Oblique Collision (2D)
  • 52.
    Distinguish between the following types of collision based on Kinetic Energy:
    a) Perfectly Elastic Collision
    b) Inelastic Collision
    c) Perfectly Inelastic Collision
  • 53.
    State Newton's Law of Collision. Define Coefficient of Restitution (e). Write its values for Elastic, Inelastic, and Perfectly Inelastic collisions.

6. System of Particles and Rotational Motion

  • 54.
    Define Rigid Body. What is the condition for a body to be rigid?
  • 55.
    Explain the following types of motion for a rigid body:
    a) Rectilinear Motion
    b) Translational Motion
    c) Circular Motion
    d) Rotational Motion
    e) Oscillatory Motion
    f) Vibrational Motion
  • 56.
    Define Centre of Mass. List the important properties or characteristics of Centre of Mass.
  • 57.
    Define Centre of Gravity. How does it differ from Centre of Mass?
  • 58.
    Define Torque (Moment of Force). Write its formula, SI Unit, and Dimensional Formula. Is it a vector?
  • 59.
    Define Angular Momentum. Write its formula in terms of linear momentum, SI Unit, and Dimensional Formula. Write the relation between Torque and Angular Momentum.
  • 60.
    State the Principle of Conservation of Angular Momentum. Give one example.
  • 61.
    Define Moment of Inertia. Write its mathematical formula, SI Unit, and Dimensional Formula.
  • 62.
    Define Radius of Gyration. Write its formula and SI Unit.
  • 63.
    State the Theorem of Perpendicular Axes and the Theorem of Parallel Axes for Moment of Inertia.
  • 64.
    Define Rolling Motion. Explain it as a combination of translation and rotation.

7. Gravitation

  • 65.
    State Kepler's Laws of Planetary Motion:
    a) Law of Orbits
    b) Law of Areas
    c) Law of Periods (Write the mathematical relation)
  • 66.
    State Newton's Law of Universal Gravitation. Write its mathematical formula and vector form. List the important Characteristics of Gravitational Force.
  • 67.
    Define Acceleration due to Gravity (\(g\)). Write its formula on the surface of the Earth. What is its SI Unit and Dimensional Formula?
  • 68.
    Define Inertial Mass and Gravitational Mass. Write their formulas. How are they related?
  • 69.
    Discuss the Variation of Acceleration due to Gravity (\(g\)) with:
    a) Altitude (Height)
    b) Depth
    c) Shape of Earth
    d) Rotation of Earth
  • 70.
    Define Gravitational Field and Gravitational Field Intensity. Write the formula, SI Unit, and Dimensional Formula.
  • 71.
    Define Gravitational Potential and Gravitational Potential Energy. Write their formulas. Are they scalar or vector quantities?
  • 72.
    Define Escape Speed. Write its formula for Earth. What is its approximate value on Earth's surface?
  • 73.
    Define Satellite. Write the formulas for:
    a) Orbital Velocity of a satellite.
    b) Time Period of Revolution of a satellite.
  • 74.
    Write the formulas for the following energies of a satellite in orbit:
    a) Kinetic Energy
    b) Potential Energy
    c) Total Energy (Mechanical Energy)
  • 75.
    Define Geostationary Satellite and Polar Satellite. Write their essential conditions and uses.
  • 76.
    What is Weightlessness in a satellite? Explain the condition under which an astronaut feels weightless.

8. Mechanical Properties of Solids

  • 77.
    Define Plasticity. Distinguish between the following types of solids:
    a) Perfectly Elastic Solids
    b) Inelastic (Plastic) Solids
    c) Partially Elastic Solids
  • 78.
    Define Stress. Write its formula, SI Unit, and Dimensional Formula.
  • 79.
    Explain the following types of Stress:
    a) Longitudinal Stress (Tensile & Compressive)
    b) Volumetric (Hydraulic) Stress
    c) Shearing (Tangential) Stress
  • 80.
    Define Strain. Why is it a dimensionless quantity? Explain its types:
    a) Longitudinal Strain
    b) Volumetric Strain
    c) Shearing Strain
  • 81.
    State Hooke's Law. Define Modulus of Elasticity.
  • 82.
    Draw the Stress-Strain Curve for a metallic wire. Define the terms:
    a) Proportional Limit
    b) Elastic Limit (Yield Point)
    c) Permanent Set
    d) Fracture Point
  • 83.
    What are Elastomers? Give two examples. How does their stress-strain curve differ from metals?
  • 84.
    Define Young's Modulus of Elasticity (Y). Write its formula, SI Unit, and Dimensional Formula.
  • 85.
    Define Bulk Modulus of Elasticity (B). Write its formula and SI Unit. What is Compressibility?
  • 86.
    Define Shear Modulus (Modulus of Rigidity, G). Write its formula and SI Unit.
  • 87.
    Write the formula for Elastic Potential Energy stored in a stretched wire. Express it in terms of stress and strain.

9. Mechanical Properties of Fluids

  • 88.
    Define Thrust and Pressure. Write their formulas, SI Units, and Dimensional Formulas.
  • 89.
    Distinguish between the following types of pressure:
    a) Atmospheric Pressure
    b) Gauge Pressure
    c) Absolute Pressure
  • 90.
    State Pascal's Law of transmission of fluid pressure.
  • 91.
    Define Density. Write its formula, SI Unit, and Dimensional Formula.
  • 92.
    Distinguish between Streamline Flow and Turbulent Flow.
  • 93.
    State Bernoulli's Principle. Write its mathematical equation.
  • 94.
    Explain the following applications of Bernoulli's Principle:
    a) Dynamic Lift of an Aeroplane
    b) Magnus Effect (Spinning Ball)
    c) Venturimeter
  • 95.
    State Torricelli's Theorem. Write the formula for the Velocity of Efflux.
  • 96.
    Define Viscosity. Define Coefficient of Viscosity and Velocity Gradient. Write their units.
  • 97.
    State Stokes' Law. Write the formula for viscous drag force. What is its importance?
  • 98.
    Define Terminal Velocity. Write its formula. Define Critical Velocity.
  • 99.
    Define Surface Tension. Write its formula, SI Unit, and Dimensional Formula. Give one example.
  • 100.
    Define Surface Energy. Define Angle of Contact.
  • 101.
    What is Capillarity (Capillary Action)? Write the formula for capillary rise. How does Detergent affect Surface Tension?

10. Thermal Properties of Matter

  • 102.
    Define Heat and Temperature. Distinguish between them. Write their SI Units and Dimensional Formulas.
  • 103.
    State the principle of a Thermometer. Write the conversion formulas between Celsius, Fahrenheit, and Kelvin scales.
  • 104.
    State the following Gas Laws:
    a) Boyle's Law
    b) Charles's Law
    c) Gay Lussac's Law
    d) Avogadro's Law
  • 105.
    Write the Ideal Gas Equation. Define the Universal Gas Constant (R). Write its SI Unit and Dimensional Formula.
  • 106.
    Define Absolute Temperature (Absolute Zero). What are the values of temperature and pressure at NTP and STP?
  • 107.
    Define Thermal Expansion. Explain the following types with their formulas:
    a) Linear Expansion (\(\alpha\))
    b) Superficial Expansion (\(\beta\))
    c) Cubical Expansion (\(\gamma\))
  • 108.
    What is the Anomalous Behaviour of Water? Write the relation between the coefficients \(\alpha\), \(\beta\), and \(\gamma\).
  • 109.
    What is Thermal Stress? Write its formula.
  • 110.
    Define Specific Heat Capacity and Molar Specific Heat Capacity. Write their formulas, SI Units, and Dimensional Formulas.
  • 111.
    Define Latent Heat (Hidden Heat). Write its formula, SI Unit, and Dimensional Formula.
  • 112.
    Define the following terms related to Change of State:
    a) Melting Point & Freezing Point
    b) Boiling Point & Condensation
    c) Sublimation & Evaporation
    d) Triple Point
  • 113.
    Explain the three modes of Heat Transfer: Conduction, Convection, and Radiation.
  • 114.
    Define Thermal Conductivity. Write its formula, SI Unit, and Dimensional Formula.
  • 115.
    Define the properties of Thermal Radiation:
    a) Reflectance (Reflective Power)
    b) Absorptance (Absorptive Power)
    c) Transmittance (Transmittive Power)
  • 116.
    Define Emissive Power and Emissivity. What is a Black Body?
  • 117.
    State Kirchhoff's Law of thermal radiation.
  • 118.
    State Stefan's Law (Stefan-Boltzmann Law). Write its mathematical formula. Write the SI Unit of Stefan's Constant (\(\sigma\)).
  • 119.
    State Wien's Displacement Law. Write its formula. Write the SI Unit of Wien's Constant (\(b\)).
  • 120.
    State Newton's Law of Cooling. Write its mathematical expression.

11. Thermodynamics

  • 121.
    Define Thermodynamics. What is meant by Thermal Equilibrium? State the Zeroth Law of Thermodynamics.
  • 122.
    Define Internal Energy. Write the formula for Work Done in thermodynamics. Is work a state function or a path function?
  • 123.
    State the First Law of Thermodynamics. Write its mathematical expression (\( \Delta Q = \Delta U + \Delta W \)). List its limitations.
  • 124.
    Define the following Thermodynamic Processes:
    a) Isothermal Process
    b) Isobaric Process
    c) Isochoric Process
    d) Adiabatic Process
    e) Polytropic Process
  • 125.
    Write the relations between \(P, V,\) and \(T\) for an Adiabatic Process involving an ideal gas (e.g., \(PV^\gamma = \text{constant}\)).
  • 126.
    What is a Cyclic Process? What is the change in Internal Energy in a cyclic process? How is the Work Done calculated from a P-V diagram?
  • 127.
    State the Second Law of Thermodynamics according to:
    a) Kelvin-Planck Statement
    b) Clausius Statement
  • 128.
    Distinguish between Reversible and Irreversible Processes. Give two examples of each.

12. Kinetic Theory of Gases

  • 129.
    Write the Ideal Gas Equation (Perfect Gas Equation). State Dalton's Law of Partial Pressures.
  • 130.
    Write the main Assumptions of the Kinetic Theory of Gases.
  • 131.
    Define Degrees of Freedom. How many degrees of freedom does a monoatomic, diatomic, and triatomic gas molecule have?
  • 132.
    State the Law of Equipartition of Energy. What is the energy associated with each degree of freedom per molecule?
  • 133.
    Define Molar Specific Heat Capacity at:
    a) Constant Volume (\(C_v\))
    b) Constant Pressure (\(C_p\))
    Write the relation between them (Mayer's Formula).
  • 134.
    Define Mean Free Path. Write its formula. On what factors does it depend?

13. Oscillations

  • 135.
    Define Oscillatory (Vibratory) Motion and Periodic Motion. Give one example of each. Is every oscillatory motion periodic?
  • 136.
    Define Time Period and Frequency. Write their mathematical relation, SI Units, and Dimensional Formulas.
  • 137.
    Define Simple Harmonic Motion (SHM). Explain how SHM is related to Uniform Circular Motion.
  • 138.
    Define Restoring Force. Write its formula for a spring-mass system. Write its SI Unit and Dimensional Formula.
  • 139.
    Distinguish between Damped Oscillations and Undamped Oscillations.
  • 140.
    What are Forced Oscillations? Define Resonance (Resonant Vibration). What is the condition for resonance to occur?
  • 141.
    Write the expression for the Time Period of a Simple Pendulum. On what factors does it depend?
  • 142.
    Write the formula for the Potential Energy, Kinetic Energy, and Total Energy of a particle executing SHM.
  • 143.
    What is the Phase of a vibrating particle? What is the phase difference between velocity and displacement in SHM?
  • 144.
    Define Spring Constant (Force Constant). Write its formula, SI unit, and dimensional formula.

14. Waves

  • 145.
    Define a Wave. Classify waves on the basis of vibration of particles into Transverse and Longitudinal waves. Give one example of each.
  • 146.
    Classify waves on the basis of medium:
    a) Mechanical Waves (Elastic Waves)
    b) Non-Mechanical Waves (Electromagnetic Waves)
    Give two examples of each.
  • 147.
    Classify waves on the basis of dimensions (1D, 2D, and 3D). Give an example for each type.
  • 148.
    Define the following components of a wave. Write their SI Units and Dimensional Formulas:
    a) Amplitude (A)
    b) Time Period (T)
    c) Frequency (\(\nu\))
  • 149.
    Define the following terms. Write their formulas, SI Units, and Dimensional Formulas:
    a) Wavelength (\(\lambda\))
    b) Wave Number (\(\bar{\nu}\))
    c) Angular Wave Number (Propagation Constant, \(k\))
  • 150.
    Define Wave Velocity (Phase Velocity) and Angular Frequency (\(\omega\)). Write the relation between Wave Velocity, Frequency, and Wavelength.
  • 151.
    Write the general equation of a Plane Progressive Wave traveling in the positive x-direction. Explain each term in the equation.
  • 152.
    Distinguish between Progressive Waves and Stationary (Standing) Waves.
  • 153.
    Define Beats. What is Beat Frequency? Write the formula for beat frequency in terms of individual frequencies.
  • 154.
    What are Nodes and Antinodes in a stationary wave? What is the distance between two consecutive nodes?