physics short definations of PHYSICS 11th class 2025 FBISE
physics short definations of PHYSICS 11th class 2025 FBISE
Below is another set of short questions with answers for each chapter of the 11th class Physics curriculum as per the Federal Board of Intermediate and Secondary Education (FBISE), Islamabad. These questions are designed to complement the previous sets, focusing on additional key concepts, alternative perspectives, and slightly varied topics to enhance understanding and exam preparation. Each chapter includes 5 new short questions with concise answers, aligned with the FBISE syllabus.
Chapter 1: Measurements
- What is a derived quantity?
Answer: A derived quantity is a physical quantity defined using combinations of base quantities, e.g., velocity (m/s) or force (kg·m/s²). - Why are significant figures important?
Answer: Significant figures indicate the precision of a measurement, ensuring accurate representation of data without implying false precision. - What is the least count of a screw gauge?
Answer: The least count is the smallest measurable distance by a screw gauge, calculated as pitch divided by the number of circular scale divisions (e.g., 1 mm / 100 = 0.01 mm). - What is dimensional analysis?
Answer: Dimensional analysis is a method to check the consistency of equations or derive relationships by comparing the dimensions of quantities. - What is meant by absolute error?
Answer: Absolute error is the difference between the measured value and the true value of a quantity.
Chapter 2: Vectors and Equilibrium
- What is a scalar quantity?
Answer: A scalar quantity has only magnitude and no direction, e.g., mass, temperature, and energy. - What is the cross product of two vectors?
Answer: The cross product is a vector perpendicular to both vectors, with magnitude AB sin θ, where θ is the angle between them. - What is meant by translational equilibrium?
Answer: Translational equilibrium occurs when the net force on a body is zero, resulting in no linear acceleration. - How is the resultant of two vectors calculated?
Answer: The resultant is found using the parallelogram law or by resolving vectors into components and applying R = √(Rₓ² + Rᵧ²). - What is the role of the moment arm in torque?
Answer: The moment arm is the perpendicular distance from the pivot to the line of action of the force, determining the torque’s magnitude (τ = F × r).
Chapter 3: Motion and Force
- What is acceleration?
Answer: Acceleration is the rate of change of velocity with time, measured in m/s². - What is the law of conservation of momentum?
Answer: The total momentum of a closed system remains constant if no external forces act on it. - What is the effect of air resistance on a projectile?
Answer: Air resistance reduces the range and height of a projectile by opposing its motion. - Define Newton’s third law of motion.
Answer: For every action, there is an equal and opposite reaction, acting on different bodies. - What is the coefficient of friction?
Answer: The coefficient of friction is a dimensionless constant that quantifies the frictional force between two surfaces (μ = F_friction / F_normal).
Chapter 4: Work and Energy
- What is a conservative force?
Answer: A conservative force is one where the work done is independent of the path taken, e.g., gravity or spring force. - How is work related to energy?
Answer: Work done on a body changes its energy, either as kinetic energy (work-energy theorem) or potential energy. - What is elastic potential energy?
Answer: Elastic potential energy is the energy stored in a deformed elastic object, given by PE = ½ kx², where k is the spring constant and x is the extension. - What is the unit of power?
Answer: The unit of power is the watt (W), equivalent to joule per second (J/s). - What happens to kinetic energy when mass doubles?
Answer: Kinetic energy doubles, as KE = ½ mv², and KE is directly proportional to mass.
Chapter 5: Circular Motion
- What is centripetal acceleration?
Answer: Centripetal acceleration is the acceleration directed toward the center of a circular path, given by a = v²/r. - What is the role of tension in circular motion?
Answer: Tension in a string or rope can provide the centripetal force for an object moving in a circular path. - What is angular displacement?
Answer: Angular displacement is the angle through which an object rotates, measured in radians. - Why is there no work done by centripetal force?
Answer: Centripetal force is perpendicular to the displacement, so the work done (W = F × d × cos 90°) is zero. - What is the frequency of circular motion?
Answer: Frequency is the number of revolutions per unit time, measured in hertz (Hz), given by f = 1/T.
Chapter 6: Fluid Dynamics
- What is streamline flow?
Answer: Streamline flow is smooth, orderly fluid motion where fluid particles follow fixed paths with constant velocity. - What is the role of surface tension in fluids?
Answer: Surface tension causes a fluid’s surface to act like a stretched membrane, affecting phenomena like capillary action. - What is Stokes’ law?
Answer: Stokes’ law states that the drag force on a small sphere moving through a viscous fluid is F = 6πηrv, where η is viscosity, r is radius, and v is velocity. - What is the significance of Bernoulli’s equation?
Answer: Bernoulli’s equation relates pressure, velocity, and height in a flowing fluid, conserving energy along a streamline. - What is the critical velocity in fluid flow?
Answer: Critical velocity is the maximum velocity at which fluid flow remains streamline; above it, flow becomes turbulent.
Chapter 7: Oscillations
- What is the restoring force in SHM?
Answer: The restoring force is the force that acts to bring the system back to its equilibrium position, proportional to displacement (F = -kx). - What factors affect the time period of a mass-spring system?
Answer: The time period depends on the mass (m) and spring constant (k), given by T = 2π√(m/k). - What is the phase of oscillation?
Answer: Phase describes the stage of an oscillation cycle, indicating the position and direction of motion. - What are free oscillations?
Answer: Free oscillations occur when a system oscillates at its natural frequency without external forces after initial disturbance. - What is the effect of damping on oscillations?
Answer: Damping reduces the amplitude of oscillations over time due to energy loss, e.g., through friction.
Chapter 8: Waves
- What is a transverse wave?
Answer: A transverse wave is one where the particles of the medium vibrate perpendicular to the direction of wave propagation, e.g., light waves. - What is the frequency of a wave?
Answer: Frequency is the number of wave cycles passing a point per unit time, measured in hertz (Hz). - What are nodes in a stationary wave?
Answer: Nodes are points of zero displacement in a stationary wave where destructive interference occurs. - What is the effect of temperature on the speed of sound?
Answer: The speed of sound increases with increasing temperature, as v ∝ √T. - What is the principle of superposition?
Answer: The principle of superposition states that when two or more waves overlap, the resultant displacement is the sum of individual displacements.
Chapter 9: Physical Optics
- What is coherent light?
Answer: Coherent light consists of waves with the same frequency, wavelength, and constant phase difference, essential for interference. - What is the fringe spacing in Young’s double-slit experiment?
Answer: Fringe spacing is the distance between consecutive bright or dark fringes, given by β = λD/d. - What is a diffraction grating?
Answer: A diffraction grating is an optical device with many closely spaced slits that disperses light into a spectrum. - Why does polarization occur only in transverse waves?
Answer: Polarization involves restricting oscillations to one plane, possible only in transverse waves with perpendicular vibrations. - What is the condition for constructive interference?
Answer: Constructive interference occurs when the path difference between two waves is an integer multiple of the wavelength (nλ).
Chapter 10: Optical Instruments
- What is the function of the eyepiece in a microscope?
Answer: The eyepiece magnifies the real image formed by the objective lens to produce a larger virtual image. - What is the normal adjustment in a telescope?
Answer: Normal adjustment is when the final image is formed at infinity, making viewing comfortable for the observer. - What is the critical angle in optics?
Answer: The critical angle is the angle of incidence in a denser medium at which the refracted ray travels along the boundary (sin θ_c = n₂/n₁). - What is the resolving power of an optical instrument?
Answer: Resolving power is the ability to distinguish between two closely spaced objects, depending on aperture and wavelength. - What is the advantage of using optical fibers?
Answer: Optical fibers enable high-speed, low-loss data transmission over long distances using total internal reflection.
Chapter 11: Heat and Thermodynamics
- What is internal energy?
Answer: Internal energy is the total energy (kinetic and potential) of the molecules in a system. - What is an adiabatic process?
Answer: An adiabatic process is one where no heat is exchanged with the surroundings (Q = 0). - What is the second law of thermodynamics?
Answer: The second law states that heat cannot flow spontaneously from a colder to a hotter body, and entropy of an isolated system increases. - What is the specific heat of a substance?
Answer: Specific heat is the amount of heat required to raise the temperature of 1 kg of a substance by 1 K (J/kg·K). - What is a heat engine?
Answer: A heat engine is a device that converts heat energy into mechanical work by operating between a hot and a cold reservoir.
Notes:
- These short questions are tailored to the FBISE 11th class Physics syllabus, focusing on additional concepts to ensure thorough coverage.
- They are concise and cover theoretical, conceptual, and application-based aspects suitable for board exam preparation.
- For further practice, students can refer to FBISE past papers, the FBISE-endorsed textbook, or online resources like www.pkmcqs.com or www.ilmkidunya.com.
- If you need more questions, numerical problems, long questions, or specific topics from any chapter, please specify, and I can provide further customized content!
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