Problem: A light ray leaves point A in Figure 1, reflects from the mirror, and reaches point B. a) How far below the top edge does the ray strike the mirror? b) What if the distance from point B to the mirror was reduced by 5 cm?

FREE Expert Solution

$\mathit{A}\mathit{n}\mathit{g}\mathit{l}\mathit{e}\mathbf{ }\mathit{o}\mathit{f}\mathbf{ }\mathit{i}\mathit{n}\mathit{c}\mathit{i}\mathit{d}\mathit{e}\mathit{n}\mathit{c}\mathit{e}\mathbf{,}\mathbf{ }{\mathit{\theta }}_{\mathbf{i}}\mathbf{=}\mathit{A}\mathit{n}\mathit{g}\mathit{l}\mathit{e}\mathbf{ }\mathit{o}\mathit{f}\mathbf{ }\mathit{r}\mathit{e}\mathit{f}\mathit{l}\mathit{e}\mathit{c}\mathit{t}\mathit{i}\mathit{o}\mathit{n}\mathbf{ }{\mathit{\theta }}_{\mathbf{r}}$

Thus, the angles marked with φ  are equal.