Question

To find the refractive index of liquid using concave mirror readings

Answer 1

Here I have proposed the procedure to find the refractive index of any liquid using a concave mirror.

Place a concave mirror on a plane surface and make sure that the principle axis of the mirror is vertical. Now horizontally hold the optical needle with a clamp stand and let the tip lie just above the pole at a distance of two times of focal length. Then remove the parallax between the needle and its image.

Now you can mark the real and inverted image of the optical needle in the mirror and measure the distance between them using a meter scale and plumb line

(Measured distance = actual radius of the concave mirror’s curvature).  

Now just add some drop of water to the concave mirror to change the position of image needle. Then adjust the screw of the clamp stand to move the position of the needle in order to remove the parallax between the needle and its shifted image.

Now, again measure the distance to find the apparent radius of the concave mirror’s curvature.

Apparatus required for the procedure:

Water

Optical needle

Spherical concave mirror

Clamp stand

Meter scale

Plumb line