Page 134 - Physics - XII

Observations

Table for angle of incidence and angle of deviation for various transparent liquids.

S. Angle of Angle of deviation (D) (in degrees)
No. incidence (i) For water For glycerine For turpentine oil

1. 30°
2. 35°

3. 40°

4. 45°
5. 50°

6. 55°
7. 60°

Graph
Plot graphs between angle of incidence (i) and angle of deviation (D), taking i along X-axis and D along
Y-axis for each transparent liquid.

Result
1. From the graphs plotted between angle of incidence and 46
angle of deviation for various transparent liquids, it is clear 44
that the angle of deviation depends on angle of incidence 42
for the given transparent liquids, and the relation between 40
angle of incidence and angle of deviation is shown on the 38
graph for the given transparent liquids. Angle of deviation D (in degree) 36

2. The graph between i and D indicates that as angle of 34 Scale used on
incidence i increases, angle of deviation D fi rst decreases, 32 X-axis, 1 cm = .....
attains a minimum value, and then again starts increasing Y-axis, 1 cm = .....
for further increase in angle of incidence i. 20 30 40 50 60 70
Angle of incidence i (in degree)
Precautions Fig. 5.3: Graph between i and D

1. The pin should be fi xed vertical.
2. Encircle the pin pricks after they are removed.
3. Pins must be at a distance of about 10 to 12 cm.

4. The angle of incidence should lie between 30° to 60°.
5. The same angle of prism should be used for all the observations.
6. Draw the arrow to indicate the incidence, the refracted, and the emergent rays.
7. The curve should be free hand and smooth which should pass through as many points as possible.

132