NEET Physics: Interference and Young's double-slit experiment Practice Questions
13 free multiple-choice questions on Interference and Young's double-slit experiment (Wave Optics) for NEET Physics, each with the correct answer and a step-by-step explanation. Attempt a question, then reveal the solution to check your reasoning.
Practice thousands more NEET questions in the app →Q1. The intensity of the light observed at a specific point in the interference pattern depends on the phase relationship between the waves. If the phase difference between the waves is 2πn, where n is an integer, the interference will be:
Show answer & explanation
Correct answer: B — Maximum constructive interference
When the phase difference is an integer multiple of 2π (2πn), the waves are perfectly in phase, resulting in maximum constructive interference (maximum intensity).
Q2. The relationship between the path difference (Δx) and the phase difference (φ) of two waves is given by:
Show answer & explanation
Correct answer: B — φ= 2π(Δx / λ)
The phase difference (φ) is directly proportional to the path difference (Δx) divided by the wavelength (λ), and the full phase difference is 2π times this ratio.
Q3. What condition must be satisfied for the formation of a stable interference pattern in the double-slit experiment?
Show answer & explanation
Correct answer: D — The sources must be coherent
Interference patterns only form when the sources are coherent (same frequency and phase relationship).
Q4. For two coherent sources producing interference, the condition for constructive interference is when the phase difference between the waves is:
Show answer & explanation
Correct answer: A — 0 or 2nπ radians
Constructive interference occurs when the phase difference between the waves is an integer multiple of 2π radians, meaning the waves are in phase.
Q5. When the path difference between two interfering waves is an integral multiple of the wavelength, the interference will be:
Show answer & explanation
Correct answer: A — Purely constructive
Constructive interference occurs when the path difference (Δx) is an integer multiple of the wavelength (λ), i.e., Δx = nλ.
Q6. In a double-slit experiment, the distance between the centers of two adjacent bright fringes is known as:
Show answer & explanation
Correct answer: A — Path difference
The distance between two consecutive bright fringes (or dark fringes) in a double-slit interference pattern is called the fringe width (β or Δy).
Q7. Consider two slits separated by a distance d. If the light travels a path difference of 2λ, what type of interference is observed at the screen?
Show answer & explanation
Correct answer: D — Complete constructive interference
A path difference of 2λ corresponds to a phase difference of 2π, resulting in complete constructive interference.
Q8. The fringe width (β) in a double-slit experiment is directly proportional to:
Show answer & explanation
Correct answer: B — The wavelength (λ)
The fringe width is given by β= λL/d. Assuming L and d are constant, the fringe width is directly proportional to the wavelength (λ).
Q9. In a double-slit experiment, the path difference between the waves arriving at a point is directly proportional to:
Show answer & explanation
Correct answer: B — The distance between the slits
The path difference (Δx) is directly proportional to the distance between the slits (d) and the angle of observation. For a fixed geometry, the path difference is proportional to d sin θ (or dsin θ in the small angle approximation, which depends on the geometry).
Q10. What is the relationship between the path difference and the phase difference in interference?
Show answer & explanation
Correct answer: B — The relationship is dependent on wavelength
The phase difference (φ) is directly proportional to the path difference (Δx), specifically φ= 2π/λ Δx.
Q11. For two coherent monochromatic sources, if the wavelength of light is halved, what happens to the fringe separation in a double-slit setup?
Show answer & explanation
Correct answer: A — It becomes four times
The fringe separation (β) is directly proportional to the wavelength (λ). If λ is halved, the fringe separation becomes four times larger. (β∝ λ)
Q12. In Young's double-slit experiment, the intensity of the resultant pattern is maximum when the condition for:
Show answer & explanation
Correct answer: C — Constructive interference
The intensity of the interference pattern is maximum when constructive interference occurs, which happens when the path difference results in the waves being in phase.
Q13. In a Young's double-slit experiment involving two coherent monochromatic sources separated by a distance d, the fringe width (β) observed on a screen placed at a distance D from the slits is given by the formula β= λD/d. If the wavelength (λ) and the distance (D) remain constant, what happens to the fringe width (β) if the separation between the slits (d) is doubled?
Show answer & explanation
Correct answer: B — β is halved
The fringe width β is inversely proportional to the slit separation d (β∝ 1/d). If d is doubled (2d), the fringe width β will be halved (β' = λD / (2d) = β/ 2).
Keep going — practice on Padhai Karlo
Padhai Karlo gives you unlimited NEET practice: chapter-wise questions, timed quizzes, and full mock tests with an All-India Rank — free to start.
Get the free Android app →