Practise 51 real Federal Board questions on Waves from 2023 to 2026. See the answer and explanation as soon as you answer.
Waves is one of the 14 main chapters in our Federal Board FSC Physics question bank (11th and 12th class), and about 10% of its real questions come from it. Tayyari Karo has 51 real questions on this chapter from 2023 to 2026; 18 are multiple choice and marked instantly, and the rest are short and long questions with a model answer. By difficulty: 38 medium, 12 easy, 1 hard.
Work through the questions below, then open the explanation for each one. Redo the ones you missed a few days later.
These are real past-paper questions. Think of your answer first, then open the explanation.
Antinode in a wave is point of:
Answer: B. Maximum displacement
An antinode is a point in a standing wave where the amplitude of oscillation (displacement) is maximum.
Location of a submarine in deep sea can be detected by:
Answer: A. Doppler effect
Sonar systems can use the Doppler shift in reflected sound waves to detect a submarine's motion and location.
Optically active crystal rotates the:
Answer: D. Polarization plane
Optically active substances rotate the plane of polarization of linearly polarized light passing through them.
If 332 waves pass through a medium in one second with speed of 332 m/s, then wave length will be:
Answer: B. 1m
λ = v/f = 332/332 = 1 m.
Maxima is produced at points where the path difference between two monochromatic waves is:
Answer: C. λ
Constructive interference (maxima) occurs when the path difference is an integral multiple of the wavelength, nλ; λ (n=1) is the only such option.
Which one of the following factors has NO effect on the speed of sound in gas?
Answer: D. Pressure
v = √(γP/ρ). Since P/ρ is constant at a given temperature (from the gas laws), pressure alone (at constant T) does not change the speed of sound.
Compare constructive and destructive interference.
Constructive interference: occurs when two waves meet in phase (path difference = nλ, a whole number of wavelengths); the resultant amplitude is the sum of individual amplitudes, giving maximum intensity.
Destructive interference: occurs when two waves meet exactly out of phase (path difference = (2n+1)λ/2, an odd multiple of half wavelength); the resultant amplitude is the difference of individual amplitudes, giving minimum (or zero) intensity.
How does the frequency of sound of a source appear when it moves: (a) Towards a stationary observer; (b) Away from a stationary observer?
The Doppler Effect for a moving source and stationary observer: let f be the actual (source) frequency, v the speed of sound, and v_s the speed of the source.
(a) Source moving towards a stationary observer: Successive wavefronts are compressed in front of the moving source (crowded closer together in the direction of motion), so the observer receives more wave crests per second — the apparent frequency increases (higher pitch): …
The full model answer is in the app.
| Session | Questions |
|---|---|
| 2026 Annual | 10 |
| 2025 1st Annual | 5 |
| 2025 2nd Annual | 7 |
| 2024 Annual | 17 |
| 2023 Annual | 12 |
51 real Federal Board (FBISE) Physics questions on Waves from 2023 to 2026, for 11th and 12th class. Each one shows the session it came from.
No. We could not find an official FBISE marking scheme for these papers, so the answers and explanations are written by Tayyari Karo for practice. Check anything important with your teacher or textbook.
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