Class 12 ISC Physics Interference of Light Board Questions
Here we provide Class 12 Physics important notes,board questions and predicted questions with Answers for chapter Interference of Light. These important notes,board questions and predicted questions are based on ISC board curriculum and correspond to the most recent Class 12 Physics syllabus. By practising these Class 12 materials, students will be able to quickly review all of the ideas covered in the chapter and prepare for the Class 12 Board examinations as well as other entrance exams such as NEET and JEE.
class 12 ISC Physics Interference of Light BoardQuestions
Interference of Light BoardQuestions
Q1
In Young’s double slit experiment show that :
β= λD/d
where the terms have their usual meaning.
solutions
The light waves that are spread out from S will fall on both S1 and S2. Because the light waves
emitted by S1 and S2 are generated from the same original source, any abrupt phase shift in S will
cause identical phase changes in the light emitted by S1 and S2. Hence spherical waves emanating
from the slits S1 and S2 will produce interference fringes on the screen GG′, as shown in the figure
1. For an arbitrary point P on the screen GG′ to correspond to a maximum, the condition is,
β= λD/d
where the terms have their usual meaning.
solutions
The light waves that are spread out from S will fall on both S1 and S2. Because the light waves
emitted by S1 and S2 are generated from the same original source, any abrupt phase shift in S will
cause identical phase changes in the light emitted by S1 and S2. Hence spherical waves emanating
from the slits S1 and S2 will produce interference fringes on the screen GG′, as shown in the figure
1. For an arbitrary point P on the screen GG′ to correspond to a maximum, the condition is,
Q2
Draw neat label diagram of Young’s double slit experiment. Show that :
β= λ/a
where the terms have their usual meaning (either for bright or dark fringe)
solutions
The light waves that are spread out from S will fall on both S1 and S2. Because the light waves
emitted by S1 and S2 are generated from the same original source, any abrupt phase shift in S will
cause identical phase changes in the light emitted by S1 and S2. Hence spherical waves emanating
from the slits S1 and S2 will produce interference fringes on the screen GG′
, as shown in the figure .
β= λ/a
where the terms have their usual meaning (either for bright or dark fringe)
solutions
The light waves that are spread out from S will fall on both S1 and S2. Because the light waves
emitted by S1 and S2 are generated from the same original source, any abrupt phase shift in S will
cause identical phase changes in the light emitted by S1 and S2. Hence spherical waves emanating
from the slits S1 and S2 will produce interference fringes on the screen GG′
, as shown in the figure .
For an arbitrary point P on the screen GG′ to correspond to a maximum, the condition is,
Q3
How is fringe width of an interference pattern in Young’s double slit experiment affected if the two
slits are brought closer to each other.
solutions
solutions
Q4
In Young’s double slit experiment using monochromatic light of wavelength 600 nm 5th bright fringe
is at a distance of 0.48 mm from the center of the pattern. If the screen is the distance of 80 cm
from the plane of the two slits calculate:
(i) distance between the 2 slits.
(ii) fringe width, i.e. fringe separation
solutions
(i) distance between the 2 slits.
(ii) fringe width, i.e. fringe separation
solutions
Q5
Define coherent source of light.
solutions
When the waves emitted by two sources have the same frequency and same phase or constant phase
difference, they are said to be coherent.
solutions
When the waves emitted by two sources have the same frequency and same phase or constant phase
difference, they are said to be coherent.
A coherent source can produce sustained interference patterns when the light waves emitting from
them superimpose, at which the positions of maxima and minima are fixed.
The light waves from two independent sources will not possess same or constant phase difference over
a time and hence they are not considered as a coherent sources.
Some of the examples for coherent sources are:
(i) Laser, lasers are commonly used as coherent sources as it uses a phenomenon called stimulated
emission to generate highly coherent light.
(ii) Small light sources are somewhat coherent. We can see interference patterns on soap bubbles and
admire the iridescence of butterfly wings because of this.
Characteristics of coherent sources are:
(i) The waves emitted must have a constant phase difference(in phase with each other)
(ii) The waves should be monochromatic
(iii) The amplitude of the waves must be same.
Q6
What should be the path difference between 2 waves reaching a point for obtaining constructive
interference in Young’s double slit experiment?
solutions
solutions
path difference=nλ
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