To Find the Refractive Index of a Liquid by Measuring the Real Depth and the Apparent Depth

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:

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.

3.  Stick the search pin into the cork on the retort stand.

4.  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.

5.  Adjust the height of the search pin until there is no parallax between the two images.

6.  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)

7.  Following the previous steps repeat the experiment 5 times using beakers of different depths.

8.  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.