key definitions from the Physics syllabus for Class 11

Below is a concise compilation of key definitions from the Physics syllabus for Class 11 under the Federal Board of Intermediate and Secondary Education (FBISE), Islamabad, covering all chapters. These definitions are aligned with the FBISE curriculum and are presented briefly with clarity for exam preparation. Note that the FBISE syllabus typically follows the National Book Foundation textbook, and the chapters listed here are based on the standard structure for 1st Year Physics (FSc Part 1). Since you requested definitions with answers, I’ll provide the definitions as they are typically asked in exams, ensuring they are short and to the point. If you need specific numericals, MCQs, or detailed explanations, please let me know!

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Chapter 1: Measurements

1. Physical Quantity: A quantity that can be measured, e.g., mass, length, time.
2. Unit: A standard quantity used to express a physical quantity, e.g., meter for length.
3. Base Unit: Fundamental units of measurement, e.g., kilogram, meter, second.
4. Derived Unit: Units derived from base units, e.g., Newton (kg·m/s²).
5. Significant Figures: Digits in a number that contribute to its precision.
6. Error: The difference between measured and actual values.
7. Precision: The closeness of repeated measurements to each other.
8. Accuracy: How close a measured value is to the true value.
9. Dimensional Analysis: A method to check the consistency of equations using units.

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Chapter 2: Vectors and Equilibrium

1. Vector: A quantity with both magnitude and direction, e.g., force, velocity.
2. Scalar: A quantity with only magnitude, e.g., mass, temperature.
3. Resultant Vector: The single vector that has the same effect as two or more vectors combined.
4. Rectangular Components: The projections of a vector along perpendicular axes (x and y).
5. Equilibrium: A state where the net force and net torque on a body are zero.
6. Torque: The rotational effect of a force, calculated as τ = r × F.
7. Dot Product: A scalar product of two vectors, A·B = AB cosθ.
8. Cross Product: A vector product of two vectors, A×B = AB sinθ.

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Chapter 3: Motion and Force

1. Displacement: The shortest distance between initial and final positions, a vector quantity.
2. Velocity: Rate of change of displacement, a vector quantity (v = Δs/Δt).
3. Acceleration: Rate of change of velocity (a = Δv/Δt).
4. Force: A push or pull that changes the state of motion (F = ma).
5. Newton’s First Law: A body remains at rest or in uniform motion unless acted upon by a net force.
6. Newton’s Second Law: The force on an object is equal to its mass times acceleration (F = ma).
7. Newton’s Third Law: For every action, there is an equal and opposite reaction.
8. Momentum: The product of mass and velocity (p = mv).
9. Impulse: The product of force and time, causing a change in momentum (J = FΔt).

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Chapter 4: Work and Energy

1. Work: The product of force and displacement in the direction of the force (W = F·d).
2. Energy: The capacity to do work, measured in joules.
3. Kinetic Energy: Energy due to motion (KE = ½ mv²).
4. Potential Energy: Energy due to position or configuration (PE = mgh).
5. Power: The rate of doing work (P = W/t).
6. Law of Conservation of Energy: Energy cannot be created or destroyed, only transformed.

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Chapter 5: Circular Motion

1. Angular Displacement: The angle through which an object rotates (θ = s/r).
2. Angular Velocity: The rate of change of angular displacement (ω = Δθ/Δt).
3. Angular Acceleration: The rate of change of angular velocity (α = Δω/Δt).
4. Centripetal Force: The force causing circular motion, directed toward the center (F = mv²/r).
5. Centripetal Acceleration: Acceleration toward the center in circular motion (a = v²/r).
6. Moment of Inertia: The mass property resisting angular acceleration (I = Σmr²).

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Chapter 6: Fluid Dynamics

1. Fluid: A substance that flows, e.g., liquids and gases.
2. Viscosity: The resistance of a fluid to flow.
3. Drag Force: The force opposing motion through a fluid.
4. Bernoulli’s Principle: As the speed of a fluid increases, its pressure decreases.
5. Equation of Continuity: The product of cross-sectional area and velocity is constant in a fluid (A₁v₁ = A₂v₂).
6. Stokes’ Law: The drag force on a sphere in a viscous fluid (F = 6πηrv).

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Chapter 7: Oscillations

1. Oscillation: Repetitive motion about an equilibrium position.
2. Simple Harmonic Motion (SHM): Motion where restoring force is proportional to displacement (F = -kx).
3. Amplitude: The maximum displacement from the equilibrium position.
4. Frequency: The number of oscillations per unit time (f = 1/T).
5. Period: The time for one complete oscillation (T = 2π√(m/k)).
6. Damping: The reduction in amplitude due to energy loss.

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Chapter 8: Waves

1. Wave: A disturbance that transfers energy through a medium.
2. Transverse Wave: A wave where particles oscillate perpendicular to the direction of propagation.
3. Longitudinal Wave: A wave where particles oscillate parallel to the direction of propagation.
4. Wavelength: The distance between two consecutive crests or troughs (λ).
5. Wave Speed: The speed of wave propagation (v = fλ).
6. Interference: The superposition of waves, causing constructive or destructive effects.
7. Standing Wave: A wave that appears stationary due to interference of two waves.

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Chapter 9: Physical Optics

1. Wavefront: A surface of points in a wave with the same phase.
2. Huygens’ Principle: Every point on a wavefront acts as a source of secondary wavelets.
3. Diffraction: The bending of waves around obstacles or through openings.
4. Interference: The combination of two or more waves to form a resultant wave.
5. Polarization: The restriction of wave oscillations to a single plane.
6. Young’s Double-Slit Experiment: Demonstrates interference of light, producing bright and dark fringes.

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Chapter 10: Thermodynamics

1. Thermodynamics: The study of heat, work, and energy transformations.
2. Internal Energy: The total energy (kinetic + potential) of a system’s particles.
3. Heat: The transfer of energy due to a temperature difference.
4. First Law of Thermodynamics: The change in internal energy equals heat added minus work done (ΔU = Q - W).
5. Second Law of Thermodynamics: Heat flows naturally from hot to cold objects; entropy increases in an isolated system.
6. Entropy: A measure of disorder in a system.
7. Isothermal Process: A process at constant temperature.
8. Adiabatic Process: A process with no heat transfer.

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Notes for Students:

• These definitions cover the essential terms typically asked in FBISE exams for Class 11 Physics. For comprehensive preparation, refer to the FBISE textbook by the National Book Foundation and practice short questions, numericals, and MCQs from past papers.
• If you need chapter-wise short questions, numerical solutions, or MCQs, let me know, and I can provide those separately.
• For further resources, websites like www.downloadclassnotes.com or www.ilmkidunya.com offer free PDF notes tailored for FBISE.
• To ensure accuracy, cross-check definitions with your textbook, as slight variations in wording may exist.

If you have specific chapters or topics you want more focus on, or if you need additional resources like solved exercises or past paper questions, please clarify, and I’ll tailor the response further!