Record experiment "Tracing the path of the rays of light through a glass prism"
Answers
Answer:
AIM - To trace the path of the rays of light through a glass prism.
MATERIAL REQUIRED-
Following are the list of materials required for this experiment:
A white sheet
Soft board
Thumb pins
4-6 all pins
Prism
Pencil
Scale
Protractor
Drawing board
PROCEDURE-
Fix a white sheet on a drawing board using drawing pins.
Place the triangular prism resting on its triangular base. Using a pencil, draw the outline of the prism.
Draw NEN normal to the face of the prism AB. make an angle between 30° and 60°.
On the line PE, fix two pins at a distance of 5cm from each other and mark these as P and Q.
Look for the images of the pins at P and Q through the other face of the prism AC.
Fix two pins at R and S such that they appear as a straight line as that of the P and Q when it is viewed from AC face of the prism.
Remove the pins and the prism.
At point F, make the points R and S meet by extending them.
PQE is the incident ray which is extended till it meets face AC. SRF is the emergent ray which is extended backward to meet at point G.
Now mark the angle of incidence ∠i, angle of refraction ∠r and the angle of emergence ∠e and ∠D as shown in the experimental setup.
Repeat the experiment for more angles between 30° and 60°.
OBSERVATIONS
At surface AB, the light ray enters and bends towards the normal on refraction.
At surface AC, the light ray bends away from the normal as it travels from one medium (glass) to the other (air).
The angle of deviation is observed. Here, the emergent ray bends at an angle towards the direction of the incident ray.
CONCLUSION -
The incident ray bends towards the normal when it enters the prism and while leaving the prism it bends away from the normal.
With the increase in the angle of incidence, the angle of deviation decreases. After attaining the minimum value, it increases with an increase in the angle of incidence.
PRECAUTIONS -
For drawing the boundary of the prism, a sharp pencil should be used.
Soft board and pointed pins should be used.
The distance between the pins should be 5cm or more.
The pins should be fixed vertically and should be encircled when they are removed from the board.
The angle of incidence should be between 30° and 60°.
The arrows drawn for incident ray, reflected ray and emergent ray should be proper.
For viewing the col-linearity of all the four pins and images, the head should be slightly titled on either side. While doing this it can appear as all are moving together.