FA2 LAB ACTIVITY-1

RELATION BETWEEN ANGLE OF INCIDENCE AND ANGLE OF REFRACTION.

Aim: Obtaining a relation between angle of incidence and angle of refraction.

Materials required: A plank, white chart, protractor, scale, small black painted plank, a semi

circular glass disc of thickness nearly 2 cm, pencil and laser light.

Procedure:

 Take wooden plank which is covered with white chart.

Draw two perpendicular lines, passing through the middle of the paper as shown in the figure. 

Let the point of intersection be O.

Mark one line as NN which is normal to the other line marked as

MM. Here MM represents the line drawn along the interface of two

media and NN represents the normal drawn to this line at ‘O’.

 Take a protractor and place it along NN in such way that its

center coincides with “O” as shown in the figure. Repeat the same

on the other side of the line NN. The angles should be indicated on

the curved line.

 Now place a semi-circular glass disc so that its diameter

coincides with the interface line (MM) and its center coincides with

the point “O”. Point a laser light along NN in such a way that the

light propagates from air to glass through the interface at point O

and observe the path of laser light coming from other side of disc

as shown in figure.

Send Laser light along a line which makes 15degrees (angle of incidence) with NN and see that passes though

point O. Measure its corresponding angle of refraction, by observing laser light coming from the other

side of the glass slab. Note these values in table. Do the same for the angles of incidence such as 20 ,

30, 40, 50  and 60 degrees and note the corresponding angle of refraction.

Observations:

Conclusion:

From the above table we will get the ratio sin i/sin r is a constant. This is Snell’s law.