In: Physics
The concepts needed to solve this problem are the law of reflection, trigonometry ratio of tangent and the concept of alternative angles.
First, draw a needful ray diagram of the situation. Use the concept of alternative angle and the formula for trigonometry ratio of tangent and solve for required angle using the law of reflection.
The formula for trigonometry ratio of tangent is,
Here, is the angle.
One of the laws of reflection is that the angle of incidence is equal to the angle of reflection.
The needful ray diagram of the situation is as follows:
In the diagram, is the incident angle at first incident, is angle of refraction at first incident, and is the glancing angle of incident of light at midpoint of second mirror.
The formula for trigonometry ratio of tangent is,
Substitute for , 11.5 cm for opposite side of angle, and 14.0 cm for adjacent side of the angle.
In the diagram, the angle and the angle r are alternative angles.
From the law of reflection, the angle of incidence is equal to the angle of reflection.
Ans:
The required value of angle of incidence is