For light diverging from a point source:
(a) | the wavefront is spherical. |
(b) | the intensity decreases in proportion to the distance squared. |
(c) | the wavefront is parabolic. |
(d) | the intensity at the wavefront does not depend on the distance. |
1. | (a), (b) |
2. | (a), (c) |
3. | (b), (c) |
4. | (c), (d) |
(a, b) Hint: The shape of the wavefronts depends on the shape of the source.
Step 1: Find the shape of the wavefronts.
Consider the diagram in which light diverges from a point source (O).
Due to the point source light propagates in all directions symmetrically and hence, the wavefront will be spherical as shown in the diagram.
Step 2: Find the intensity of wavefronts.
lf power of the source is P, then intensity of the source will be,
Where, r is radius of the wavefront at any time.
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