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Class 12
Physics
Wave Optics
what is the shape of the wavefront in each of the...

Question:
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.

Answer:

(a) Light diverging from a point source.

The geometrical shape of the wavefront in case of light diverging from a point source will be diverging spherical wavefront . It can be shown as,

(b) Light emerging out of a convex lens when a point source is placed at its focus.

When a point source is placed at the focus of a convex lens, the rays emerging from the lens are parallel. Therefore, the wavefront must be plane, as shown in figure,

(c) The portion of the wavefront of light from a distant star intercepted by the Earth.

The source of light (i.e. star) is very far off (i.e. at infinity), the wavefront intercepted by the earth will be a plane wavefront, as shown above.

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Question:
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.

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Question: 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.

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Question:
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.