1 Answer | Add Yours
The figure is below.
Let the incoming ray of light coming from the left side and reflecting on a horizontal surface. The wave front of the incoming light ray is the geometrical place of all the points in a ray that oscillate with the same phase. This wave front is thus perpendicular to the direction of propagation.
The incoming wave front is `|AB|` . Because in the figure (as the second law of reflection states)
and the angles:
`/_A A'B'` and `/_r` have perpendicular sides
`/_BA A'` and `/_i` have perpendicular sides
it means `/_A A' B' -=/_BA A'`
Also from the same considerations we have
`/_B'A A' -=/_BA' A`
Thus because also
`/_AB'A' = /_A'BA =90 deg`
the triangles `AB'A'-=A'BA rArr |A'B'|-=|AB|`
Thus the second law of reflection means in mathematical terms that the reflected front wave is congruent with the incoming front wave.
We’ve answered 319,643 questions. We can answer yours, too.Ask a question