Haldis aims a laser pointer at a small mirror taped to the wall, trying to light up a poster across the room. To place the bright spot, she needs the reflected beam's exact angle.
You have the law of reflection and the from-the-normal convention. This lesson is practice: given any one angle at a flat mirror, find the others, fast.
Step one: get the given angle measured from the normal.
If the angle is given from the surface, the angle from the normal is 90° minus it.
Step two: the angle of reflection equals the angle of incidence.
Step three: if the question asks for an angle from the surface, it is 90° minus the angle from the normal.
Haldis's beam arrives at 25° from the normal.
It reflects at 25° from the normal, which is 65° from the mirror surface.
A ray arrives at a flat mirror at 25° to the normal. Find the angle of reflection, and the angle the reflected ray makes with the mirror surface.
The angle of incidence is 25°, already measured from the normal.
The angle of reflection equals it: 25°.
The surface angle is 90 − 25 = 65.
The angle of reflection is 25°, and the reflected ray makes 65° with the surface.
A beam strikes a flat mirror at 68° from the surface. Find the angle of reflection.
The given angle is from the surface, so convert it: 90 − 68 = 22.
The angle of incidence is 22° from the normal.
The angle of reflection equals it.
The angle of reflection is 22°, measured from the normal.
A ray hits a flat mirror in a dance studio at 35° from the normal. Enter the angle of reflection, in degrees.
A ray hits a flat hand mirror at 20° from the normal. Enter the angle, in degrees, between the reflected ray and the mirror's surface.
A beam strikes a shop window's flat glass at 64° from the surface. Enter the angle of incidence, in degrees.
A laser beam arrives at a flat locker mirror at 52° from the normal. Enter the angle of reflection, in degrees.
A ray strikes a still puddle's flat surface at 15° from the surface. Enter the angle, in degrees, between the reflected ray and the normal.
A ray arrives at a flat glass tabletop at 8° from the normal. Enter the angle, in degrees, between the reflected ray and the surface.
A beam strikes a flat mirror at 58° from the surface. Enter the angle of reflection, in degrees, measured from the normal.
A ray arrives at a flat bathroom mirror at 28° from the normal. Which description gives the reflected ray?
A ray arrives at a flat mirror at 47° from the normal. Enter the angle, in degrees, between the reflected ray and the mirror's surface.