To Find The Refractive Index Of A Liquid By Measuring The Real Depth And The
Apparent Depth Of An Object In The Liquid.
Equipment needed:
1. Beaker
2. Search pin
3. Object pin
4. Cork
5. Plane mirror
Method:
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1. Fill the beaker fully with water and
place the object pin at the centre of
the base.
2. Place the plane mirror across the top
of the beaker with the reflective side
facing
upwards and with the water touching
the back of the mirror.
Stick the search pin into the cork on the retort stand.
Adjust the position of the search pin until its image in the plane mirror is in line with
the image of the object pin in the water.
Adjust the height of the search pin until there is no parallax between the two images.
Measure : The distance from the object pin to the top of the water (real depth)
The distance from the search pin to the top of the water (apparent depth)
Following the previous steps repeat the experiment 5 times using beakers of different
depths.
Now use the formula: Refractive Index (n) = real depth / apparent depth, to find the
refractive Index of water for each set of values.
Results
Real Depth (cm)
Apparent Depth (cm)
n = Real Depth
Apparent Depth
Average n =
Conclusion:
All results were found to be approx 1.33. Therefore within the limits of experimental
error it was found that the Refractive Index of water = 1.33.
Precautions:
1. Make sure the beakers can be filled right to the top with water.
2. Make sure the water is touching the back of the mirror.
3. Take care when locating the position of no parallax.
4. Take care when measuring the distances.
5. Make sure you use a plane mirror.
6. Make sure your line of view is perpendicular to the surface of the medium.