Physics 2001 JAMB Past Questions - Question 11: A ray of light strikes a plane mirror at an angle, of incidence of 35. If the mirror is rotated through 10, through what angle is the reflected ray' rotated?

Correct Answer

C

Explanation

When a ray of light strikes a plane mirror, the angle of incidence (the angle between the incident ray and the normal to the mirror) is equal to the angle of reflection (the angle between the reflected ray and the normal to the mirror). This is known as the law of reflection.

In your scenario, the angle of incidence is 35 degrees. According to the law of reflection, the angle of reflection will also be 35 degrees.

Now, if the mirror is rotated through an angle of 10 degrees, the angle between the mirror's normal and the incident ray also changes by 10 degrees. To find the new angle of incidence, you can simply subtract 10 degrees from the original angle of incidence:

New angle of incidence = 35 degrees - 10 degrees = 25 degrees.

So, the reflected ray will also be rotated by the same amount, which is 10 degrees. The angle of reflection will be 10 degrees.