The Class 11 Physics – Chapter 1: Physical World MCQs consist of 370 questions in total, divided into 4 well-structured parts. While the first three parts contain 100 MCQs each, this final part includes 70 questions. The numbering begins from 1 in each part for clarity. These MCQs are based on the NCERT/CBSE Class 11 Physics syllabus and are extremely helpful for board exams, competitive tests (NEET, JEE, etc.), and quick concept review.
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Correct Answer: Electromagnetic Induction
Explanation: Transformers use electromagnetic induction to change the voltage level of an alternating current.
Correct Answer: Superconductivity
Explanation: Superconductivity allows electric power to be transmitted over long distances with minimal loss due to zero electrical resistance.
Correct Answer: Cathode emission
Explanation: The electron beam in a cathode ray tube (CRT) is produced by cathode emission, where electrons are emitted from a heated cathode.
Correct Answer: Generator
Explanation: A generator converts mechanical energy into electrical energy using the principle of electromagnetic induction.
Correct Answer: Lorentz Force Law
Explanation: The Lorentz Force Law explains how charged particles move in a magnetic field, experiencing a force perpendicular to their velocity and the magnetic field.
Correct Answer: Capacitor
Explanation: A capacitor is used to store electrical energy temporarily in an electric field between its plates.
Correct Answer: Faraday’s Law
Explanation: Faraday’s Law of Electromagnetic Induction describes how electricity is generated in a hydroelectric dam by moving a conductor through a magnetic field.
Correct Answer: The range of electromagnetic waves
Explanation: The electromagnetic spectrum refers to the range of all possible frequencies of electromagnetic radiation.
Correct Answer: Galvanometer
Explanation: A galvanometer measures electric current using the deflection of a coil in a magnetic field, based on the principles of electromagnetism.
Correct Answer: By using magnetic fields to control the flow of electricity
Explanation: An electromagnetic relay uses magnetic fields to control the flow of electricity in circuits, allowing for the switching of currents.
Correct Answer: A rule that governs the behavior of natural phenomena
Explanation: A physical law is a statement based on repeated experimental observations that describes an aspect of the world. It always applies under the same conditions and implies a causal relationship involving its elements.
Correct Answer: They are based on empirical evidence
Explanation: Physical laws are grounded in empirical evidence gathered through observation and experimentation, and they are consistently validated through these means.
Correct Answer: The Theory of Evolution
Explanation: The Theory of Evolution is a scientific theory explaining the diversity of life on Earth, while Newton’s Law of Gravitation, the Law of Conservation of Energy, and Ohm’s Law are all physical laws describing specific physical phenomena.
Correct Answer: They form the basis for understanding the natural world
Explanation: Physical laws provide a fundamental framework for understanding and predicting natural phenomena, enabling the development of scientific knowledge and technology.
Correct Answer: They can be revised or replaced as new evidence emerges
Explanation: While physical laws are generally reliable, they can be revised or replaced if new empirical evidence or better theoretical frameworks emerge.
Correct Answer: The Law of Conservation of Energy
Explanation: The Law of Conservation of Energy states that energy cannot be created or destroyed, only transformed from one form to another, ensuring the total energy in a closed system remains constant.
Correct Answer: Mathematical equations
Explanation: Physical laws are frequently expressed using mathematical equations because these provide precise and unambiguous descriptions of the relationships between physical quantities.
Correct Answer: Newton’s Third Law
Explanation: Newton’s Third Law states that for every action, there is an equal and opposite reaction, highlighting the mutual forces of action and reaction between two interacting bodies.
Correct Answer: It ensures the predictability and consistency of physical phenomena
Explanation: Symmetry in physical laws helps ensure that the laws of physics are consistent and predictable across different situations and scales, providing a fundamental framework for understanding the universe.
Correct Answer: Reproducibility
Explanation: Reproducibility is central to the nature of physical laws, as it ensures that experiments and observations yield consistent results across different conditions and times, reinforcing the reliability of scientific theories.
Correct Answer: They predict the exact outcome of an event
Explanation: Deterministic laws predict the exact outcome of an event based on initial conditions and known principles, with no randomness involved.
Correct Answer: Classical Mechanics
Explanation: Classical Mechanics, governed by Newton’s laws, is an area of physics that relies heavily on deterministic principles to predict the motion and behavior of objects.
Correct Answer: They incorporate elements of randomness
Explanation: Probabilistic laws account for elements of randomness and uncertainty, predicting the likelihood of various outcomes rather than exact results.
Correct Answer: Quantum Mechanics
Explanation: Quantum Mechanics deals with probabilistic laws, where the behavior of particles is described in terms of probabilities rather than definite outcomes.
Correct Answer: Deterministic laws predict exact outcomes, while probabilistic laws predict likelihoods
Explanation: The key difference is that deterministic laws predict precise outcomes given specific conditions, whereas probabilistic laws predict the likelihood of various outcomes.
Correct Answer: A mathematical function describing the probabilities of a particle’s properties
Explanation: In quantum mechanics, the wave function is a mathematical function that describes the probability distribution of a particle’s properties, such as position and momentum.
Correct Answer: Newton’s Second Law of Motion
Explanation: Newton’s Second Law of Motion is an example of a deterministic law, as it predicts the exact acceleration of an object based on the forces acting upon it and its mass.
Correct Answer: The exact position and momentum of a particle cannot be simultaneously known
Explanation: Heisenberg’s Uncertainty Principle states that there is a fundamental limit to the precision with which the position and momentum of a particle can be known simultaneously, highlighting the probabilistic nature of quantum mechanics.
Correct Answer: They account for the inherent uncertainty in particle properties
Explanation: Probabilistic laws are crucial in quantum mechanics because they account for the inherent uncertainty and randomness in the behavior and properties of subatomic particles.
Correct Answer: The likelihood of finding an electron in a particular region around the nucleus
Explanation: The concept of a probabilistic law is illustrated by the likelihood of finding an electron in a specific region around the nucleus, as quantum mechanics describes electron positions in terms of probability distributions rather than definite locations.
Correct Answer: The invariance of physical laws under a shift in time
Explanation: Symmetry in physical laws often involves invariance under transformations. In this case, the invariance of physical laws under a shift in time is an example of temporal symmetry, meaning the laws of physics are the same at any point in time.
Correct Answer: Translational symmetry
Explanation: The conservation of momentum is a consequence of translational symmetry, which means that the laws of physics do not change if the position of the system is shifted uniformly in space.
Correct Answer: Conservation of angular momentum
Explanation: The conservation of angular momentum is associated with rotational symmetry. If a system’s physical properties are unchanged under rotations, angular momentum is conserved.
Correct Answer: Noether’s theorem
Explanation: Noether’s theorem formalizes the relationship between symmetries and conservation laws. It states that every differentiable symmetry of the action of a physical system corresponds to a conservation law.
Correct Answer: Electroweak symmetry breaking
Explanation: Electroweak symmetry breaking is an example of broken symmetry in physics. It occurs in the Standard Model of particle physics, where the unified electroweak force separates into the electromagnetic and weak forces at low energies.
Correct Answer: It ensures laws are universal and invariant under certain transformations
Explanation: Symmetry is crucial in formulating physical laws because it ensures that these laws are universal and invariant under certain transformations, providing a deeper understanding of the fundamental principles governing the universe.
Correct Answer: Parity symmetry
Explanation: Parity symmetry, or reflection symmetry, is associated with the invariance of physical laws under spatial reflection. This means the laws of physics remain unchanged if coordinates are inverted.
Correct Answer: Invariance of physical laws under Lorentz transformations
Explanation: Lorentz symmetry implies that the laws of physics are invariant under Lorentz transformations, which include changes in an observer’s velocity and position in space-time, as described by special relativity.
Correct Answer: Gauge symmetry
Explanation: Gauge symmetry is primarily responsible for the conservation of electric charge. It is a fundamental symmetry that involves transformations of the electromagnetic field, ensuring charge conservation.
Correct Answer: A symmetry between fundamental particles and their superpartners
Explanation: Supersymmetry is a theoretical symmetry in quantum mechanics that proposes a relationship between fundamental particles (bosons and fermions) and their superpartners, which have different spin properties. This symmetry aims to address various unresolved issues in particle physics.
Correct Answer: A pendulum swings back and forth without friction
Explanation: In a frictionless pendulum, the total mechanical energy (potential plus kinetic energy) remains constant as it swings back and forth, exemplifying the conservation of energy.
Correct Answer: The total momentum of a closed system remains constant
Explanation: The principle of conservation of momentum states that in a closed system with no external forces, the total momentum before and after any event remains the same.
Correct Answer: Kirchhoff’s law
Explanation: Kirchhoff’s law, specifically Kirchhoff’s current law, states that the total current entering a junction equals the total current leaving the junction, which is a manifestation of the conservation of electric charge.
Correct Answer: Two ice skaters pushing away from each other
Explanation: When two ice skaters push off each other, their combined momentum before and after the push remains constant, illustrating the conservation of momentum.
Correct Answer: Potential energy to kinetic energy
Explanation: When a stretched spring is released, the stored potential energy is converted into kinetic energy as the spring returns to its natural length, demonstrating the conservation of energy.
Correct Answer: The total charge remains constant over time
Explanation: The conservation of charge in an electrical circuit means that the total amount of electric charge remains constant over time, ensuring charge is neither created nor destroyed.
Correct Answer: The total energy remains constant
Explanation: The conservation of energy principle states that within a closed system, the total amount of energy remains constant, though it can change forms (e.g., from kinetic to potential energy).
Correct Answer: Newton’s third law of motion
Explanation: Newton’s third law of motion (“For every action, there is an equal and opposite reaction”) reflects the conservation of linear momentum, as the action and reaction forces lead to equal and opposite changes in momentum.
Correct Answer: A pendulum swinging in a vacuum
Explanation: In a vacuum, a pendulum would continue swinging indefinitely without air resistance or friction, thereby demonstrating the conservation of mechanical energy.
Correct Answer: The number of electrons lost equals the number of electrons gained
Explanation: In electrochemical reactions, the conservation of charge is maintained by ensuring that the number of electrons lost by the oxidizing agent equals the number of electrons gained by the reducing agent.
Correct Answer: Physical laws are applicable throughout the universe
Explanation: The universality of physical laws means that these laws are consistent and applicable throughout the entire universe, regardless of location or conditions.
Correct Answer: The principle of relativity
Explanation: The principle of relativity, which states that the laws of physics are the same for all observers in all inertial frames of reference, supports the universality of physical laws.
Correct Answer: They apply to both terrestrial and celestial bodies
Explanation: Newton’s laws of motion are universal, meaning they apply to all objects, whether on Earth (terrestrial) or in space (celestial), illustrating their broad applicability.
Correct Answer: It applies to gravitational and electric fields
Explanation: The inverse-square law, which states that the strength of a force decreases with the square of the distance, applies universally to both gravitational and electric fields, demonstrating the consistent nature of physical laws.
Correct Answer: Newton’s Law of Universal Gravitation
Explanation: Newton’s Law of Universal Gravitation exemplifies the universality of physical principles as it applies to interactions ranging from atomic particles to massive celestial bodies across the cosmos.
Correct Answer: It applies uniformly in all inertial reference frames
Explanation: The constancy of the speed of light in all inertial reference frames is significant because it underscores the universality of physical laws, as articulated in Einstein’s theory of relativity.
Correct Answer: Energy transfer across different forms
Explanation: The conservation of energy supports its universality, as energy can transform from one form to another (e.g., kinetic to potential energy) while the total energy remains constant across different domains.
Correct Answer: They apply to all electric and magnetic fields
Explanation: Maxwell’s equations demonstrate the universality of physical laws by applying to all electric and magnetic fields, regardless of location, showing consistency in describing electromagnetic phenomena.
Correct Answer: They govern all physical and chemical processes
Explanation: Thermodynamic laws illustrate universality as they govern all physical and chemical processes, regardless of the specific system or conditions, emphasizing their broad applicability.
Correct Answer: Symmetry principles guide the formulation of physical laws
Explanation: Symmetry is crucial because it guides the formulation of physical laws, ensuring that these laws are invariant and universally applicable under transformations such as rotations and translations, reflecting the consistency of nature’s laws.
Correct Answer: To unify the electromagnetic, weak, and strong nuclear forces
Explanation: The primary goal of the Grand Unified Theory (GUT) is to unify the three fundamental forces of nature—electromagnetic, weak, and strong nuclear forces—into a single theoretical framework, providing a more comprehensive understanding of particle interactions.
Correct Answer: Gravitational force
Explanation: The Grand Unified Theory aims to unify the electromagnetic, weak, and strong nuclear forces, but it does not include the gravitational force, which is addressed separately by theories such as General Relativity and attempts at unification like String Theory.
Correct Answer: Strings
Explanation: String Theory proposes that the fundamental building blocks of the universe are one-dimensional “strings” rather than point particles. These strings can vibrate at different frequencies, leading to the various particles and forces observed in nature.
Correct Answer: Different particles
Explanation: In String Theory, different vibrational states of strings represent different particles. The various patterns of vibration determine the properties and types of particles, such as electrons, quarks, and neutrinos.
Correct Answer: Theory of Everything (TOE)
Explanation: The Theory of Everything (TOE) seeks to unify all four fundamental forces, including gravity, into a single comprehensive framework, providing a complete understanding of all physical phenomena in the universe.
Correct Answer: String Theory
Explanation: String Theory is a theoretical framework that aims to incorporate both quantum mechanics and general relativity, providing a unified description of all fundamental forces and particles by describing them as vibrational states of strings.
Correct Answer: Lack of experimental evidence
Explanation: A major challenge facing the development of the Grand Unified Theory (GUT) is the lack of experimental evidence to support the unification of the electromagnetic, weak, and strong nuclear forces, making it difficult to validate the theory.
Correct Answer: Gravitational force
Explanation: The gravitational force remains separate in the unification attempts of both the Grand Unified Theory (GUT) and the Standard Model of particle physics. Integrating gravity with the other forces is a key objective of theories like String Theory.
Correct Answer: The symmetry between particles and their superpartners
Explanation: In the context of unification theories, “supersymmetry” refers to the proposed symmetry between particles and their superpartners. Supersymmetry predicts that each particle has a corresponding partner with different spin properties, potentially aiding in the unification of forces.
Correct Answer: Large Hadron Collider (LHC)
Explanation: The Large Hadron Collider (LHC) is the experimental facility most associated with testing the predictions of String Theory and the Grand Unified Theory. It accelerates particles to high energies and collides them to observe rare phenomena and potential new particles predicted by these theories.