Free Superposition and Interference MCQs with Answers

• A. the vector sum of the individual displacements
• B. always zero
• C. always double one of them
• D. the larger of the two displacements

Explanation: Displacements add algebraically, so waves in phase reinforce and waves in antiphase cancel, and afterwards each wave continues unchanged.

• A. of different frequencies
• B. coherent, keeping a constant phase relationship
• C. very far apart
• D. of unequal amplitude

Explanation: If the phase difference between the sources drifts, the positions of the bright and dark fringes shift too fast to be seen and the pattern…

• A. an odd number of half wavelengths
• B. a whole number of wavelengths
• C. always zero
• D. one quarter of a wavelength

Explanation: A path difference of a whole number of wavelengths brings the waves back into phase, so the crests coincide and the amplitude is a…

• A. of exactly the same frequency overlap
• B. of slightly different frequencies overlap
• C. travel in opposite directions
• D. have very different amplitudes

Explanation: The two waves drift in and out of phase, so the loudness rises and falls at a rate equal to the difference between the two frequencies.

• A. 4 Hz
• B. 258 Hz
• C. 516 Hz
• D. 0.5 Hz

Explanation: The beat frequency is simply the difference between the two frequencies, so 260 minus 256 gives 4 beats per second.

• A. half a wavelength
• B. one whole wavelength
• C. a quarter of a wavelength
• D. three quarters of a wavelength

Explanation: A path difference of a whole number of wavelengths brings the two waves back into phase so their crests coincide, giving constructive…

• A. π
• B. 2π
• C. π/2
• D. π/4

Explanation: Destructive interference occurs when the waves arrive out of phase by an odd multiple of π radians, such as π radians, so their…

• A. diffraction
• B. dispersion
• C. interference
• D. polarization

Explanation: Colours in a thin film arise from interference between light reflected from the upper and lower surfaces of the film.

• A. same wavelength
• B. same amplitude of vibration
• C. same wave length with constant phase difference
• D. same amplitude and wavelength

Explanation: Coherent sources have the same frequency or wavelength and maintain a constant phase difference, which keeps the interference pattern…

• A. no interference fringes are observed
• B. no diffraction fringes are observed
• C. no fringes observed
• D. interference pattern not disturbed

Explanation: Double-slit interference requires light from both slits, so covering one slit removes the interference fringes.

• A. bright fringes are wider than dark fringes
• B. dark fringes are wider than bright fringe
• C. both dark and bright fringes are of equal width
• D. central fringes are brighter than the outer fringes

Explanation: For equally spaced interference fringes, the positions of successive bright and dark fringes are equally separated, so their widths are…

• A. alternate dark and bright fringes will be seen
• B. coloured fringes will be seen
• C. no interference fringes will be seen
• D. impossible to predict

Explanation: Different colours in white light have different wavelengths, so their bright and dark fringes occur at different positions, producing…

• A. polarization
• B. constructive interference
• C. destructive interference
• D. diffraction

Explanation: A crest meeting a trough gives displacements in opposite directions, so they cancel partially or completely by destructive interference.

• A. interference fringes only
• B. diffraction fringes only
• C. both interference and diffraction fringes
• D. polirized frringes

Explanation: In a real double-slit arrangement, each slit diffracts the light and the waves from the two slits interfere, so interference fringes…

• A. 42Hz
• B. 7 Hz
• C. 256Hz
• D. 262Hz

Explanation: Beat frequency is the absolute difference between the frequencies of two close sounds, fbeat = |f1 - f2|.

• A. diffraction of sound waves
• B. constructive and destructive interference
• C. polarization
• D. destructive interference

Explanation: Beats arise when two waves of slightly different frequencies superpose, repeatedly producing constructive interference and destructive…

• A. silence zone
• B. interference
• C. beats
• D. resonance

Explanation: The repeated rise and fall of sound loudness occurs when two close frequencies interfere, producing alternating constructive and…

• A. decreases
• B. increases
• C. remains unchanged
• D. becomes zero

Explanation: Superposition changes the displacement and amplitude of overlapping waves, but it does not change the wave speed because the speed is…

• A. constructive interference
• B. destructive interference
• C. beats
• D. resonance

Explanation: A silence zone forms where two sound waves arrive with opposite phase and cancel one another, producing destructive interference and…

• A. the sum of the frequencies of two tuning forks
• B. the difference of the frequencies of two tuning forks
• C. the ratio of the frequencies of two tuning forks
• D. the frequency of either of the two tuning forks

Explanation: The beat frequency is the absolute difference between the two source frequencies, fbeat = |f1 - f2|, measured in hertz or beats per…