WorksheetsB.Sc. I Chapter III
Total questions: 10
Worksheet time: 5mins
A parallel beam of white light is incident on a thin film of oil of thickness 2×10−7 m. The normally reflected light is observed and it shows the first dark fringe at a certain wavelength. If refractive index of oil is 1.4, ------- the wavelength of colour is absent.
5600 A0
2800 A0
1400 A0
5800 A0
The fringes obtained in case of Newton’s rings experiment are ----
localized fringes
of equal thickness
localized and equal thickness
delocalized
A parallel beam of light of wavelength 6000A0 is incident on a thin glass plate of refractive index 1.5. The angle of refraction in the plate is 600. Calculate the minimum thickness of the plate so that it appears completely dark in reflected light.
4000 A0
2000 A0
1000 A0
6000 A0
The fringes observed in case of wedge shaped thin film are ----
equally spaced
of equal thickness
localised
equally spaced, localized and of equal thickness
When a progressive wave gets reflected from the surface of a denser medium, its phase changes by---
900
1800
3600
450
When a ray of light gets reflected from the surface of a denser medium, then additional path difference introduced is ---
2λ
4λ
23λ
λ
The distance between successive Newton’s rings experiment ---- as the order n of the fringes increases.
increases
decreases
remains constant
none of these
In case of Newton’s rings experiment if the ring pattern is formed due to reflected light then the centre of the ring pattern is ----
dark
bright
dark or bright
semi-dark
A beam of monochromatic light of wavelength 5.82×10−7 m falls normally on a glass wedge, makes fringes with fringe width 0.2 cm, then ----- is the number of fringes per cm of the wedge length.
5 per cm
10 per cm
2.5 per cm
1 per cm
For maximum of interference the value of path difference is ---
(n+21)λ
(2n+1) 2λ
2nλ
nλ
