Advertisements
Advertisements
Question
Explain the construction of plane wavefront using Huygens’ principle.
Solution
a. A plane wavefront is formed when point of observation is very far away from the primary source.
b. Let PQR represent a plane wavefront at any instant. According to Huygens’ principle,all the points on this wavefront will act as secondary sources of light sending out secondary wavelets in the forward direction.
c. Draw hemispheres with P, Q, R…. as centres and ‘ct’ as radius. The surface tangential
to all such hemispheres is P1Q1R1…. at instant ‘t’. It is a new wavefront at time ‘t’.
d. The plane wavefronts is propagated as plane waves in homogeneous isotropic medium.They are parallel to each other.
e. PP1N1, QQ1N2, RR1N3 are the wave normals at P, Q, R respectively. These wave normals show the direction of propagation of plane wavefront.
f. The new wavefront P1Q1R1 is parallel to primary wavefront PQR.
APPEARS IN
RELATED QUESTIONS
Using Huygens's construction of secondary wavelets explain how a diffraction pattern is obtained on a screen due to a narrow slit on which a monochromatic beam of light is incident normally.
What is the shape of the wavefront in the following case?
The portion of the wavefront of light from a distant star was intercepted by the Earth.
You have learnt in the text how Huygens’ principle leads to the laws of reflection and refraction. Use the same principle to deduce directly that a point object placed in front of a plane mirror produces a virtual image whose distance from the mirror is equal to the object distance from the mirror.
Use Huygens' principle to verify the laws of refraction.
Using Huygens’ principle, verify the laws of reflection at a plane surface.
Use Huygens’s principle to explain the formation of diffraction pattern due to a single slit illuminated by a monochromatic source of light.
Huygens' principle of secondary wavelets may be used to
(a) find the velocity of light in vacuum
(b) explain the particle behaviour of light
(c) find the new position of a wavefront
(d) explain Snell's Law
Answer the following question.
Define the term wavefront. Using Huygen's wave theory, verify the law of reflection.
Define a wavefront. Using 'Huygens' principle, draw the shape of a refracted wavefront, when a plane wave is incident on a convex lens.
Define the term 'wavefront of light'. A plane wavefront AB propagating from a denser medium (1) into a rarer medium (2) is incident of the surface P1P2 separating the two media as shown in fig.
Using Huygen's principle, draw the secondary wavelets and obtain the refracted wavefront in the diagram.
What is the phase difference between any two points lying on the same?
The inverse square law of intensity is valid for a
Wavefront means
Huygen's conception of secondary waves ______.
Figure shows a standard two slit arrangement with slits S1, S2, P1, P2 are the two minima points on either side of P (Figure). At P2 on the screen, there is a hole and behind P2 is a second 2-slit arrangement with slits S3, S4 and a second screen behind them.
Consider a point at the focal point of a convergent lens. Another convergent lens of short focal length is placed on the other side. What is the nature of the wavefronts emerging from the final image?
What is the shape of the wavefront on earth for sunlight?
Two light beams of intensities in the ratio of 9 : 4 are allowed to interfere. The ratio of the intensity of maxima and minima ______.
Using Huygen's wave theory of light, show that the angle of incidence is equal to the angle of reflection. Draw a neat and labelled diagram.
Represent diagrammatically how the incident planar wavefronts of wavelength λ pass through an aperture of size d, when d is approximately equal to λ.
