Advertisements
Advertisements
Question
Explain the construction of plane wavefront using Huygens’ principle.
Advertisements
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
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.
State Huygen’s principle.
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.
The refractive indices of water and diamond are `4/3` and 2.42 respectively. Find the speed of light in water and diamond. (c = 3x108 m/s)
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.
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?
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 Huygen's construction, relation between old and new wavefront is ______.
Answer the following question briefly and to the point:
What is the phase difference between any two points lying on the same wavefront?
The inverse square law of intensity is valid for a
Wavefront means
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?
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 ______.
According to Huygens’s principle, the amplitude of secondary wavelets is ______.
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.
Represent diagrammatically how the incident planar wavefronts of wavelength λ pass through an aperture of size d, when d is approximately equal to λ.
