Q1. In thin film interference, which of the following will not affect the interference pattern? (2022)
Solution:
While thickness, wavelength, and angle of incidence affect the interference pattern, the color of the light source does not directly affect the pattern itself.
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Q2. What is the wavelength of light if the first-order maximum occurs at an angle of 30° in a double-slit experiment with a slit separation of 0.1 mm and a screen distance of 1 m? (2019)
Solution:
Using the formula λ = d sin θ / m, where d = 0.1 mm, θ = 30°, and m = 1, we find λ = 0.1 mm * sin(30°) = 0.1 mm * 0.5 = 0.05 mm = 0.2 mm.
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Q3. In a Michelson interferometer, what happens to the fringe pattern if one of the mirrors is moved away from the beam splitter? (2020)
Solution:
Moving one mirror changes the path length, causing the fringe pattern to shift to the right.
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Q4. In a Newton's ring experiment, if the radius of the first dark ring is found to be r, what is the radius of the second dark ring? (2020)
Solution:
The radius of the dark rings in Newton's rings is proportional to the square root of the ring number. Thus, the second dark ring will have a radius of 2r.
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Q5. If the distance between the slits in a double-slit experiment is halved, what happens to the angular position of the first-order maximum? (2023)
Solution:
If the slit separation d is halved, the angle θ for the first-order maximum (d sin θ = λ) will increase, effectively doubling the angle.
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Q6. What is the angle of diffraction for the first minimum in a single-slit diffraction pattern if the slit width is 0.5 mm and the wavelength of light is 500 nm? (2023)
Solution:
The angle for the first minimum is given by sin θ = λ/a, where a is the slit width. Thus, sin θ = 500 nm / 0.5 mm = 0.001, leading to θ ≈ 30°.
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Q7. In a double-slit experiment, if the screen is moved further away from the slits, what happens to the fringe separation? (2019)
Solution:
Moving the screen further away increases the fringe separation, as fringe width β = λD/d; increasing D increases β.
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Q8. In a diffraction pattern produced by a single slit, what happens to the central maximum when the slit width is decreased? (2022)
Solution:
Decreasing the slit width increases the diffraction angle, causing the central maximum to become wider.
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Q9. What is the effect on the interference pattern if the wavelength of light used in a double-slit experiment is increased? (2023)
Solution:
Increasing the wavelength increases the fringe width, as fringe width β is directly proportional to the wavelength.
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Q10. In a thin film of air between two glass plates, which of the following colors will be least affected by interference? (2022)
Solution:
Red light has the longest wavelength and is least affected by interference effects in thin films compared to shorter wavelengths.
