Oscillations and Waves — NEET Physics MCQs with answers

Oscillations and Waves is a Class 11 Physics chapter in the NEET (UG) syllabus. NEET720 has 1,064 reviewed practice questions on it, each with a quick answer and a step-by-step explanation. The 8 questions below are free and fixed, so you can bookmark this page; the full chapter, plus mistake tracking and spaced revision, is in the app.

Topics covered

SHM kinematics and dynamics · Energy in SHM · Pendulums and spring systems · Damped, forced oscillations and resonance · Wave motion and speed · Superposition and interference · Standing waves: strings and organ pipes · Beats · Physical pendulum · Superposition of SHMs · Wave energy and intensity · Wave reflection · Sonometer · Wave energy and power · Wave equation · General wave properties · SHM kinematics · Speed of sound · Spring-mass systems · Damped and forced oscillations · Wave motion basics · Stretched strings · Standing waves in strings · Resonance tube · Standing waves in organ pipes · Compound (physical) pendulum · Doppler effect · Wave power · Forced Oscillations · Simple harmonic motion · Resonance · Waves on a string · Sound intensity · Organ pipes · Superposition principle · Wave interference · Oscillations · Waves · SHM · Simple pendulum

8 free Oscillations and Waves practice questions with answers

Choose an answer in your head before opening it. Each explanation says why the correct option is right and, where relevant, why the tempting wrong option is wrong.

1. Question 1 · medium · Damped, forced oscillations and resonance

   Soldiers marching in step across a bridge are traditionally ordered to break step. This precaution is taken to avoid which physical effect?

   • A.Resonance, if the marching frequency matches the bridge's natural frequency, driving up the amplitude of the bridge's oscillation dangerously
   • B.Destructive interference between soldiers' steps cancelling the bridge's support forces
   • C.Doppler shift in the bridge's vibration frequency as soldiers move across it
   • D.Beats between the soldiers' footsteps and the bridge's natural vibration causing audible throbbing
   Show answer and explanation

   Answer: A. Resonance, if the marching frequency matches the bridge's natural frequency, driving up the amplitude of the bridge's oscillation dangerously

   Marching in step applies a periodic force at the step frequency; if this matches the bridge's natural frequency, resonance builds up dangerously large oscillations, so soldiers break step to avoid it.

   A bridge is an elastic structure with its own natural frequency of vibration. Synchronised footsteps act as a periodic external force. If the step frequency coincides with the bridge's natural frequency, the forced-oscillation amplitude grows large (resonance), which can damage or even collapse the structure (a classic real historical hazard). Breaking step randomises the forcing frequency so no sustained resonant build-up occurs. Beats, interference-cancellation of support forces, and Doppler shift are unrelated mechanisms.

   Common mistake: Confusing resonance with beats or Doppler effect

2. Question 2 · easy · Damped, forced oscillations and resonance

   A simple pendulum swinging freely in air (with no external periodic driving force) gradually loses amplitude due to air resistance. This kind of oscillation, where amplitude decreases with time and no external driver is present, is called:

   • A.forced oscillation
   • B.undamped simple harmonic motion
   • C.resonant oscillation
   • D.damped oscillation
   Show answer and explanation

   Answer: D. damped oscillation

   An oscillator left to swing freely while losing energy to a resistive force (like air drag), with no external periodic driver, undergoes damped oscillation — its amplitude decays over time.

   Damped oscillation occurs when a system oscillates under its own restoring force while continuously losing mechanical energy to a resistive force (such as air resistance or internal friction), causing the amplitude to shrink over successive cycles, typically exponentially for light damping. This is distinct from forced oscillation (which requires an external periodic driving force) and resonance (a special case of forced oscillation with large amplitude response). Undamped SHM is the idealised case with no energy loss at all.

   Common mistake: Confusing damped oscillation (free, decaying) with forced oscillation (externally driven).

3. Question 3 · medium · Damped, forced oscillations and resonance

   A child on a swing is given small periodic pushes. To build up the largest possible amplitude with the least effort, the pusher should time the pushes so that the pushing frequency:

   • A.is much higher than the swing's natural frequency, so pushes occur many times per swing
   • B.equals the swing's natural frequency, so each push is in phase with the swing's own motion
   • C.is much lower than the swing's natural frequency, so pushes are spaced far apart
   • D.is irrelevant, since any periodic push eventually builds the same maximum amplitude
   Show answer and explanation

   Answer: B. equals the swing's natural frequency, so each push is in phase with the swing's own motion

   Maximum amplitude build-up with minimum applied force occurs at resonance, when the driving (pushing) frequency matches the system's natural frequency, so each push adds constructively to the ongoing motion.

   This is a classic resonance scenario: the swing has its own natural frequency determined by its effective pendulum length. Pushing at exactly this frequency means every push arrives when the swing is moving in the same direction as the push, continuously adding energy in phase and building up amplitude efficiently — this is resonance. Pushing at any other frequency means pushes sometimes oppose the swing's motion, wasting effort and limiting the achievable amplitude for a given push strength.

   Common mistake: Believing faster or slower pushing (rather than matched-frequency pushing) builds amplitude more effectively.

4. Question 4 · easy · Standing waves: strings and organ pipes

   In a stationary (standing) wave, which statement correctly distinguishes a node from an antinode?

   • A.A node is a point of maximum displacement amplitude; an antinode never moves.
   • B.A node is a point that always has zero displacement due to destructive superposition of the oppositely travelling waves, while an antinode is a point of maximum displacement amplitude.
   • C.Nodes and antinodes both have the same non-zero amplitude but differ only in phase.
   • D.A node is a point of maximum velocity but zero acceleration, independent of displacement.
   Show answer and explanation

   Answer: B. A node is a point that always has zero displacement due to destructive superposition of the oppositely travelling waves, while an antinode is a point of maximum displacement amplitude.

   A standing wave is formed by two identical waves travelling in opposite directions. At a node the two waves are always exactly out of phase (destructive interference for displacement), giving permanent zero displacement; at an antinode they are always in phase, giving maximum displacement amplitude.

   A standing wave results from superposition of a wave and its reflection travelling in opposite directions. At certain fixed points, the two component waves are always equal and opposite in displacement, so the resultant displacement is zero at all times — these are nodes. Midway between nodes, the two waves are always in phase, so the resultant amplitude is the sum of the two amplitudes — these are antinodes, the points of maximum displacement amplitude. Option A reverses the definitions. Option C wrongly claims equal non-zero amplitude everywhere, ignoring that nodes are defined precisely by zero amplitude. Option D confuses the kinematic description (a node does have zero velocity and maximum restoring acceleration is irrelevant to its definition) with the actual defining property, which is displacement amplitude.

   Common mistake: Swapping the words node and antinode, or thinking both points have equal non-zero amplitude

5. Question 5 · medium · Standing waves: strings and organ pipes

   In a standing wave on a stretched string, what happens to energy across a node, averaged over a complete cycle?

   • A.Energy flows steadily from one side of the node to the other, just as in a travelling wave.
   • B.No net energy crosses a node; energy remains trapped, oscillating between kinetic and potential forms within each loop.
   • C.Energy is entirely converted to heat at each node due to destructive interference.
   • D.Energy crosses the node only during the half-cycle when the node is momentarily at rest.
   Show answer and explanation

   Answer: B. No net energy crosses a node; energy remains trapped, oscillating between kinetic and potential forms within each loop.

   Unlike a travelling wave (which carries energy continuously in one direction), a standing wave has zero net energy flux averaged over a cycle at every point, including nodes — the two component travelling waves carry equal energy in opposite directions, cancelling on average, so energy simply oscillates locally between KE and PE within each loop.

   A standing wave is the superposition of two equal travelling waves moving in opposite directions, each carrying the same magnitude of power. At any cross-section (including a node), the net time-averaged power transmitted is the difference of these two equal-and-opposite powers, which is zero — no net energy is transported along the string. Instead, within each loop (between adjacent nodes), the total mechanical energy continuously converts between kinetic energy (maximum when the string passes through its undisplaced position) and potential (elastic) energy (maximum at extreme displacement), oscillating locally at twice the wave frequency, but not migrating past the node into the neighbouring loop. Option A wrongly imports travelling-wave energy transport into a standing wave. Option C confuses a mathematical node in displacement with energy dissipation, which does not occur without damping. Option D misunderstands that this is an averaged (not instantaneous) statement.

   Common mistake: Assuming energy travels through a standing wave the same way it does through a travelling wave

6. Question 6 · easy · Superposition and interference

   According to the principle of superposition, when two or more waves overlap at a point in a medium, the resultant displacement of that point is:

   • A.The vector (algebraic) sum of the displacements each wave would produce individually at that point
   • B.The average of the individual displacements produced by each wave
   • C.Always equal to the displacement of whichever wave has the larger amplitude
   • D.The product of the individual displacements of each wave
   Show answer and explanation

   Answer: A. The vector (algebraic) sum of the displacements each wave would produce individually at that point

   The superposition principle states that overlapping waves simply add their displacements algebraically at each point, independent of each other's presence.

   The principle of superposition (valid for linear media) states that when two or more waves overlap, the net displacement at any point and instant is the algebraic (vector) sum of the displacements that each wave would individually produce at that point, as if the other waves were absent. This underlies interference, beats, and standing waves. Averaging, taking the maximum, or multiplying are all incorrect operations.

   Common mistake: Believing waves average out or that the larger wave alone survives

7. Question 7 · easy · Wave motion and speed

   In a longitudinal wave travelling through a medium, the particles of the medium oscillate:

   • A.Perpendicular to the direction of wave propagation
   • B.Parallel to the direction of wave propagation, creating compressions and rarefactions
   • C.In a circular path around the direction of wave propagation
   • D.Randomly, with no fixed relation to the direction of wave propagation
   Show answer and explanation

   Answer: B. Parallel to the direction of wave propagation, creating compressions and rarefactions

   In longitudinal waves (e.g., sound), particles vibrate back and forth along the same line as wave travel, forming compressions and rarefactions.

   A longitudinal wave, such as a sound wave in air, involves particle displacement parallel to the direction of energy/wave propagation, alternately compressing and rarefying the medium. This contrasts with transverse waves (e.g., a wave on a string, or light), where particle displacement is perpendicular to propagation.

   Common mistake: Mixing up transverse and longitudinal particle motion directions

8. Question 8 · easy · Wave motion and speed

   Sound waves cannot travel through vacuum, but light waves can. This difference arises because:

   • A.Sound waves are transverse and vacuum only supports longitudinal waves
   • B.Sound is a mechanical (longitudinal) wave requiring a material medium to transmit particle vibrations, while light is an electromagnetic wave that needs no medium
   • C.Sound waves travel faster than light waves, so vacuum cannot support them
   • D.Light has a lower frequency than sound, allowing it to pass through vacuum
   Show answer and explanation

   Answer: B. Sound is a mechanical (longitudinal) wave requiring a material medium to transmit particle vibrations, while light is an electromagnetic wave that needs no medium

   Sound is a mechanical wave needing particles of a medium to vibrate and pass on the disturbance; electromagnetic waves like light involve oscillating fields and need no medium.

   Mechanical waves (sound, waves on strings/water) rely on the physical displacement and restoring forces between medium particles, so they cannot exist without a material medium — hence no sound in vacuum. Electromagnetic waves consist of oscillating electric and magnetic fields that self-propagate without needing any material carrier, so light travels through vacuum (indeed fastest through vacuum). Options B, C, D attach the effect to irrelevant properties like speed, frequency, or wave-type classification.

   Common mistake: Attributing the vacuum restriction to speed or frequency rather than the mechanical nature of sound

Questions about Oscillations and Waves for NEET

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Questions are original NEET720 compositions reviewed for correctness, syllabus fit and option quality. Counts update as the bank grows (1,064 active practice questions in this chapter today).