NCERT Class XII Chapter
Wave Optics
Questions With Solutions
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Question : 2
Total: 21
What is the shape of the wavefront in each of the following cases:
(a) Light diverging from a point source.
(b) Light emerging out of a convex lens when a point source is placed at its focus.
(c) The portion of the wavefront of light from a distant star intercepted by the Earth.
(a) Light diverging from a point source.
(b) Light emerging out of a convex lens when a point source is placed at its focus.
(c) The portion of the wavefront of light from a distant star intercepted by the Earth.
Solution:
(a) Spherical wavefront : All particles vibrating in same phase will lie on a sphere.
(b) Plane wavefront : Light will be a parallel beam after passing through the convex lens.
(c) Plane wavefront : Light rays from a distant star are nearly parallel as a small portion of a huge spherical wavefront is nearly plane.
(b) Plane wavefront : Light will be a parallel beam after passing through the convex lens.
(c) Plane wavefront : Light rays from a distant star are nearly parallel as a small portion of a huge spherical wavefront is nearly plane.
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