Question

Experiment 8: Reflection and Refraction

* From the results describe and draw graphs to show how the focal lengths of the concave and convex mirrors are obtained.

Experimental Procedure:

A laser beam ray is shining toward a plane mirror surface, we draw the incident ray and reflected ray on a piece of paper with a normal line drawn already. Then we use a protractor to measure the incident angle and reflected angle.

cylindrical mirror results:

	Concave mirror	Convex mirror
Focal length	6 cm	-6cm
Radius of curvature using compass	x	x

Answer 1

Hello,

Image formed by plane mirror:

When light rays fall on the object, it reflectes and falls on the shining surface of the plane mirror. Then it bounces back in the same medium as shown in figure. when you extend this reflected ray behind the mirror it meets the straight line drawn from the object. This is the position of the image. The angle made by the incident ray with normal is the angle of incidence and angle made by the reflected ray with normal is the angle of reflection. Both are equal. Hence, we will get upright, same size but virtual image that is behind the plane mirror.

cylindrical mirror:

In this case you have to find the radius of curvature of the cylindrical mirror by using compass. Hence you have to use a compass to draw a circle that matches the curvature of the mirror that you have used for practical.

According to theory, radius of the curvature is the twice of the focal length.

Ray diagram for concave mirror as

For convex mirror

Thanking You!