1. What is lateral shift in Fresnel's Biprism experiment?
The angle of refraction in the biprism
The distance between the biprism and the screen
The change in wavelength of sodium light
Lateral shift is the sideways displacement of the fringe pattern due to misalignment of the optical components, such as the biprism or the slit, relative to the optical bench.
2. How can lateral shift be removed in Fresnel's Biprism experiment?
By increasing the intensity of the light source
By using white light instead of sodium light
By changing the refracting angle of the biprism
Lateral shift can be removed by adjusting the position of the slit, biprism, or eyepiece to ensure proper alignment along the optical axis of the setup.
3. Why is d1 and d2 taken in Fresnel's Biprism experiment?
To calculate the wavelength of white light
To determine the angle of the biprism
To measure the intensity of light
d1 is the distance from the slit to the biprism, and d2 is the distance from the biprism to the screen, used to calculate the fringe width and the separation of virtual sources.
4. What is a coherent source in the context of Fresnel's Biprism?
A coherent source is a light source that produces waves with a constant phase difference and the same wavelength, essential for producing stable interference patterns.
A source that emits light of multiple wavelengths
A source that produces polarized light
A source with high intensity but no phase relation
5. What is an incoherent source?
A source that emits monochromatic light
A source used for diffraction experiments
An incoherent source produces light waves with random phase differences, resulting in no stable interference pattern.
A source that produces coherent waves
6. What is fringe width in Fresnel's Biprism experiment?
Fringe width is the distance between consecutive bright or dark fringes in the interference pattern, given by β = λD/d, where λ is the wavelength, D is the distance from the slit to the screen, and d is the separation of virtual sources.
The thickness of the biprism
The width of the light source
The distance between the slit and the biprism
7. What is a Fresnel's Biprism?
A diffraction grating for spectral analysis
A mirror that reflects light to create fringes
A lens used to focus light
Fresnel's Biprism is an optical device made of two thin prisms joined at their bases, used to create two virtual coherent sources from a single light source to produce interference fringes.
8. On which principle does Fresnel's Biprism work?
Fresnel's Biprism works on the principle of interference of light, where two virtual coherent sources created by refraction produce an interference pattern.
Reflection of light from a surface
Diffraction of light through a narrow slit
Polarization of light waves
9. What is bench error in Fresnel's Biprism experiment?
The error due to using white light
The error in the refracting angle of the biprism
Bench error is the misalignment or inaccuracy in the optical bench setup, such as improper positioning of the slit, biprism, or eyepiece, leading to errors in measurements like fringe width.
The error in calculating the wavelength
10. Why does sodium light have two wavelengths?
Sodium light has two wavelengths (589.0 nm and 589.6 nm, known as the D1 and D2 lines) due to the transition of electrons between specific energy levels in sodium atoms.
Due to the use of two different light sources
Because of the biprism splitting the light
Due to polarization effects in the light
11. What happens to the fringe pattern if white light is used instead of sodium light?
The fringes disappear completely
The fringes remain the same as with sodium light
Using white light produces a central white fringe with colored fringes on either side due to the overlap of interference patterns from multiple wavelengths, unlike the distinct monochromatic fringes with sodium light.
The fringes become wider and brighter
12. Why is the refracting angle of Fresnel's Biprism kept small?
To reduce the wavelength of the light
To make the biprism easier to manufacture
To increase the intensity of the light
The refracting angle is kept small (about 0.5°) to ensure that the two virtual sources are close enough to produce clear and measurable interference fringes.
13. What is fringe shift in Fresnel's Biprism experiment?
The lateral movement of the light source
The change in the refracting angle of the biprism
The variation in the intensity of the fringes
Fringe shift is the displacement of the interference pattern when a transparent medium, like a thin film, is introduced in the path of one of the interfering beams, altering the optical path length.
14. How is fringe shift fixed in Fresnel's Biprism experiment?
By rotating the biprism
Fringe shift is fixed by adjusting the position of the medium or compensating for the optical path difference, often by using a compensator plate or recalibrating the setup.
By changing the wavelength of the light
By increasing the light intensity
15. What is the least count of a micrometer in Fresnel's Biprism experiment?
0.001 mm
1 mm
0.1 mm
The least count of a micrometer is typically 0.01 mm or 0.005 mm, depending on the precision of the micrometer used to measure distances like fringe width.
16. What is interference in the context of Fresnel's Biprism?
The scattering of light by particles
The reflection of light from a surface
The bending of light around corners
Interference is the phenomenon where two or more waves superpose to form a resultant wave of greater or lower amplitude, producing bright and dark fringes in the biprism experiment.
17. What are constructive and destructive interference?
Both produce the same type of fringes
Constructive interference occurs when waves are in phase, resulting in increased amplitude (bright fringes), while destructive interference occurs when waves are out of phase, resulting in reduced amplitude (dark fringes).
Constructive interference reduces amplitude, destructive increases it
