Question

Vittorio needs to clean the dusty mirror hanging on the wall before he can use it, but he would like to clean as little of the mirror as possible.

A.) Vittorio would like to be able to see the logo on his shirt. Draw the incident and reflected rays showing the light from the logo reflecting off the mirror into his eyes. The rays should meet at the point on the mirror that needs cleaning.

Draw the vectors, for the reflected and incident ray, starting and ending at the surface of the mirror respectively. The location and orientation of the vectors will be graded.

B.) Vittorio would like to be able to check whether his shoelaces are tied. Draw the incident and reflected rays showing the light from his shoelaces reflecting off the mirror into his eyes. Again, the rays should meet at the point on the mirror that needs cleaning.

(See the hints from Part A if you need help.)

Draw the vectors, for the reflected and incident ray, starting and ending at the surface of the mirror respectively. The location and orientation of the vectors will be graded.

Answer 1

Concepts and reason

The concept used in this question is law of reflection.

Firstly, draw the diagram of the incident and reflecting rays from the mirror between eyes and logo.

Finally, draw the diagram of the incident and reflecting rays from the mirror between eyes and shoes.

Fundamentals

The law of reflection states that the incident ray, the reflected ray, and the normal to the surface of the mirror, all lie in the same plane.

Also, the angle of incidence is equal to the angle of reflection.

(A)

The figure 1 shows the path of light from the logo to the eyes of the person.

The angle made by the rays point O with the normal to the surface of the mirror are equal. The vertical distances of the point O from logo and from O to eyes is same as the angle must be same.

(2)

The figure 1 shows the path of light from the shoelace to the eyes of the person.

The angle made by the rays point O with the normal to the surface of the mirror are equal. The vertical distances of the point O from shoelace and from O to eyes is same as the angle must be same.

Ans: Part A

The ray diagram is as follows:

Answer 2

The figure 1 shows the path of light from the logo to the eyes of the person.

The angle made by the rays point O with the normal to the surface of the mirror are equal. The vertical distances of the point O from logo and from O to eyes is same as the angle must be same.

(2)

The figure 1 shows the path of light from the shoelace to the eyes of the person.

The light ray always travels in straight lines so that there will be no deviation in its path while reaching the mirror from the shoelace or while reaching the eyes from the mirror.

Answer 3

You have to drag out the arrows all the way to the mirror.

A)Top Ray 7 deg. Bottom Ray 173 deg

B)Top Ray 25 deg. Bottom Ray 155 deg