Interference (Young's double-slit experiment and expression for fringe width, coherent sources,..) NEET Questions

Physics - Optics

Interference (Young's double-slit experiment and expression for fringe width, coherent sources,..) MCQ Questions


7.
The intensity at any point in the interference pattern of two coherent sources of intensity I₀ each, where the phase difference is φ, is:
A.
I = 4I₀ cos²(φ/2)
B.
I = 2I₀ cos²(φ)
C.
I = I₀ sin²(φ)
D.
I = I₀ + cos(φ)
😑 View Answer Rough Work Error
ANSWER :
A. I = 4I₀ cos²(φ/2)
8.
If two waves of amplitudes a₁ and a₂ interfere, the maximum and minimum intensities are in the ratio:
A.
(a₁ - a₂) : (a₁ + a₂)
B.
(a₁² + a₂²) : (a₁² - a₂²)
C.
a₁ : a₂
D.
(a₁ + a₂)² : (a₁ - a₂)²
😑 View Answer Rough Work Error
ANSWER :
D. (a₁ + a₂)² : (a₁ - a₂)²
9.
Two sources of light are said to be coherent if they have:
A.
Same amplitude but different frequencies
B.
The same frequency and a constant phase difference (which doesn't change with time)
C.
Different frequencies but same amplitude
D.
Same phase but different frequencies
😑 View Answer Rough Work Error
ANSWER :
B. The same frequency and a constant phase difference (which doesn't change with time)
10.
Two independent sources of light (e.g., two sodium lamps) cannot produce sustained interference because:
A.
They have different colors
B.
Sources are too far apart
C.
Light has very high speed
D.
They are not coherent — phase changes randomly and rapidly with time (~10⁻¹⁰ s)
😑 View Answer Rough Work Error
ANSWER :
D. They are not coherent — phase changes randomly and rapidly with time (~10⁻¹⁰ s)
11.
When two incoherent sources are superposed, the resultant intensity at any point is:
A.
Simply the sum of the individual intensities (I₁ + I₂)
B.
Zero at all points
C.
Determined by the path difference
D.
4I₀ at all points
😑 View Answer Rough Work Error
ANSWER :
A. Simply the sum of the individual intensities (I₁ + I₂)
12.
In Young's double-slit experiment, the two slits act as coherent sources because:
A.
The slits are exactly the same size
B.
The slits are illuminated by sunlight
C.
The slits are very close together
D.
They are derived from the same original source, so any phase change in the original source affects both slits identically
😑 View Answer Rough Work Error
ANSWER :
D. They are derived from the same original source, so any phase change in the original source affects both slits identically