Two mirrors are arranged as shown in the drawing.Light is incident from the right on the first mirror at an angle of 70°.The light reflects toward the second mirror and is reflected at angle .Determine the angle
A)25°
B)65°
C)45°
D)35°
E)55°

Question

Two mirrors are arranged as shown in the drawing.Light is incident from the right on the first mirror at an angle of 70°.The light reflects toward the second mirror and is reflected at angle .Determine the angle 
A)25° 
B)65° 
C)45° 
D)35° 
E)55°

Quizplus · Accepted Answer

Using the law of reflection at the first mirror, the angle of reflection is equal to the angle of incidence and therefore is 70°. 
At the second mirror, the angle of incidence is the angle of reflection from the first mirror, which is 70°. 
Using the law of reflection again, the angle of reflection is equal to the angle of incidence, which is 70°. 
Therefore, the angle between the incident ray and the reflected ray from the second mirror is 70° + 70° = 140°. 
Since the angle between the incident ray and the normal is 90°, the angle between the reflected ray and the normal is 180° - 140° = 40°. 
Finally, using the law of reflection for the second mirror, the angle of reflection is equal to the angle of incidence, which is 40°. 
Therefore, the angle 11ec9dfd_8b1d_90b1_8d20_ffc56304147b_TB6393_11 is 180° - (70° + 40°) = 70°.

Two Mirrors Are Arranged as Shown in the Drawing