A mirror lies flat on a table.A beam of light strikes the mirror with an angle of incidence or 15°,the reflected ray being to the right of the incident beam.The right edge of the mirror is then lifted so that the mirror now makes a 5° angle with the horizontal.What is the resulting angle between the incident beam and the reflected beam?

Question

Quizplus · Accepted Answer

When the mirror lies flat on the table, the angle of incidence (i) equals the angle of reflection (r), resulting in the reflected beam being 15° to the right of the incident beam.

After lifting the right edge of the mirror, the angle of incidence increases to 20°, and the angle of reflection also increases to 20°, resulting in the reflected beam still being 15° to the right of the incident beam.

Therefore, the resulting angle between the incident beam and reflected beam is 20° (i + r), which corresponds to choice B.

A Mirror Lies Flat on a Table