MEDIUM
JEE Main/Advance
IMPORTANT
Earn 100

What is the effect on the fringe width of interference fringes in a Young's double slit experiment due to each of the following operations:

(a) The screen is moved away from the plane of the slits.

(b) the (monochromatic) source is replaced by another (monochromatic) source of shorter wavelength.

(c) The separation between the two slits is increased.

(d) The width of two slits is slightly increased.

[In each operation, take all parameters, other than the one specified to remain unchanged.]

Important Questions on Wave Optics

MEDIUM
JEE Main/Advance
IMPORTANT
Two slits separated by a distance of 1 mm are illuminated with a red light of wavelength 6.5×107 m. The interference fringes are observed on a screen placed 1 m from the slits. Find the distance between the third dark fringe and the fifth bright fringe on the same side of the central maxima.
MEDIUM
JEE Main/Advance
IMPORTANT
In a Young’s double slit experiment, the fringe width is found to be 0.4 mm. If the whole apparatus is immersed in water of refractive index 43 without disturbing the geometrical arrangement, what is the new fringe width?
EASY
JEE Main/Advance
IMPORTANT
Find the angular fringe width in a Young’s double slits experiment with blue-green light of wavelength 6000 Å. The separation between the slits is 3.0 × 103 m.
MEDIUM
JEE Main/Advance
IMPORTANT
A source emitting light of wavelengths 480 nm and 600 nm is used in a double slit interference experiment. The separation between the slits is 0.25 mm and the interference is observed on a screen placed at 150 cm from the slits. Find the linear separation between the first maximum (next to the central maximum) corresponding to the two wavelengths.
HARD
JEE Main/Advance
IMPORTANT

A flint glass and a crown glass are fitted on the two slits of a double slit apparatus. The thickness of the strips is 0.40 mm and the separation between them is 0.12 cm. The refractive index of flint glass and crown glass are 1.62 and 1.52, respectively, for light of wavelength 480 nm which is used in the experiment. Interference is observed on a screen at a distance of one meter.

(a) What would be the fringe-width?

(b) At what distance from the geometrical centre will the nearest maximum be located?

EASY
JEE Main/Advance
IMPORTANT
Find the thickness of a plate which will produce a change in optical path equal to half the wavelength λ of the light passing through it normally. The refractive index of the plate is μ.
 
MEDIUM
JEE Main/Advance
IMPORTANT
A soap film of thickness 0.3 μm appears dark when seen by the refracted light of wavelength 580 nm. What is the index of refraction of the soap solution if it is known to be between 1.3 and 1.5?
MEDIUM
JEE Main/Advance
IMPORTANT
A parallel beam of light of wavelength 560 nm falls on a thin film of oil (refractive index=1.4). What should be the minimum thickness of the film so that it weakly transmits the light?