As performed in the real lab:
A drawing board, rectangular glass slab, office pins, sheet of white paper, a protractor and sharply pointed pencil.
- Fix a sheet of white paper on a drawing board with drawing pins. Place the given glass slab nearly in the middle of the sheet.
- Mark the boundary of the glass slab with a sharp pencil and label it as PQRS after removing the slab from its position.
- On the line PQ mark a point E and draw a normal N1EN2 at it. Draw a line AE making angle AEN1 with the normal.The angle should neither too small nor too large (say about 40 degree).
- Now place the glass slab again on its boundary PQRS and fix two pins A and B vertically about 10 cm apart on the line AE (say points A and B).
- Look through the glass slab along the plane of the paper from the side SR and move your head until the images of the two pins A and B are seen clearly. Closing your one eye ,adjust the position of your head in such a way that the images of the pins A and B lie in the same straight line.
- Fix two other pins C and D vertically in such a way that the images of the pins A and B and pins C and D, all these four, lie in the same straight line. Ensure that the feet of the pins ( not their heads ) lie in the same straight line.
- Remove the slab and also the pins from the board and encircle the pin-pricks on the paper,with a sharp pencil.
- Join the points D and C and produce the line DC towards the slab so that it meets the boundary line RS at the point F. Join the points e and F. Thus for the incident ray represented by line AE, the refracted ray and the emergant ray are represented by EF and FD respectively.
- On the line RS draw a normal N1'FN2' at point F. Now, with a protractor, measure angle AEN1, angle FEN2 and angle DFN2' labelled as angle i, angle r and angle e respectively.
- Now place the glass slab at some other position on the sheet of paper fixed on the board and repeat all the above steps again taking another angle of incidence.
- Measure the angle of incidence i.e angle of refraction, angle of emergence, again.
- Make a record of your observations in the observation table as shown below.
Observation Table :
As performed in the simulator:
- Click on Show values checkbox to display the refractive indices of air and glass, angle of incidence and angle of refraction.
- Move the Observer to get an approximate emergent ray.
- Note down the angle of incidence, angle of refraction and angle of emergence in the Observation Table.
- To view the actual emergent ray click on Emergent Ray checkbox.
- Use the slider to change the angle of incidence, and repeat the above steps.