[h3]The Normal[/h3] [ul] [li]A normal is an imaginary line drawn perpendicular to a surface. (90[degree] to a surface).[/li] [li]It is very ease to draw in 2D.[/li] [li]It is the line directly in between the incident and the reflected waves.[/li] [/ul] [h3]The laws of Reflection[/h3] [b]1)[/b] The angle of incidence is equal to the angle of reflection [img src='https://res.cloudinary.com/deylrqt2d/image/upload/v1487947450/angle_incidence_is_angle_reflection_w0hnbd.svg' style='width:100vw;'] [ul] [li]Angles are always measured between the ray and the normal.[/li] [li]The [b]N[/b], represent the [b]Normal[/b].[/li] [li][b]i[degree][/b] represents the [b]incidence ray[/b], the ray coming towards the plane.[/li] [li][b]r[degree][/b] represent the [b]reflected ray[/b], the ray reflected from the plane.[/li] [/ul] [code] [b]i[degree] is equal to r[degree][/b]. [/code] [b]2)[/b]The incident ray, the reflected ray and the normal, all lie on the same plane. (Flat surface). [hr] [h3]A periscope[/h3] [img src='https://res.cloudinary.com/deylrqt2d/image/upload/v1487951335/periscope_rg8skd.svg' style='width:100vw;'] Only through the reflected rays do you see an image.