Advertisements
Advertisements
प्रश्न
Explain the construction of plane wavefront using Huygens’ principle.
Advertisements
उत्तर
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
संबंधित प्रश्न
What is the shape of the wavefront in the following case?
Light emerging out of a convex lens when a point source is placed at its focus.
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.
Consider a plane wave front incident on a thin convex lens. Draw a proper diagram to show how the incident wave front traverses through the lens and after refraction focusses on the focal point of the lens, giving the shape of the emergent wave front.
Use Huygens' principle to verify the laws of refraction.
Use Huygens’s principle to explain the formation of diffraction pattern due to a single slit illuminated by a monochromatic source of light.
When the width of the slit is made double the original width, how would this affect the size and intensity of the central diffraction band?
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
Derive the law of reflection using Huygen’s Wave Theory.
Define the term wavefront. Using Huygen’s wave theory, verify the law of reflection.
A plane wave front AB propagating from denser medium (1) into a rarer medium (2) is incident on the surface P1P2 separating the two media as shown in fig.
Using Huygen’s principle, draw the secondary wavelets and obtain the refracted wave front in the diagram.
According to Huygens principle, ______.
Answer the following question briefly and to the point:
What is the phase difference between any two points lying on the same wavefront?
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.
For light diverging from a point source ______.
- the wavefront is spherical.
- the intensity decreases in proportion to the distance squared.
- the wavefront is parabolic.
- the intensity at the wavefront does not depend on the distance.
Is Huygen’s principle valid for longitudinal sound waves?
Two light beams of intensities in the ratio of 9 : 4 are allowed to interfere. The ratio of the intensity of maxima and minima ______.
What type of wavefronts are associated with a source infinity?
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.
What type of wavefronts are associated with a point source of light?
Represent diagrammatically how the incident planar wavefronts of wavelength λ pass through an aperture of size d, when d is approximately equal to λ.
