Question

To find the refractive index of water using concave mirror

Answer 1

Materials required:The given convex lensThe given liquid- waterPlane mirrorRetort standPointerMercuryMeter scaleChina dishReal Lab Procedure:To find the focal length of the convex lens:The plane mirror is placed horizontally on the base of the retort stand with its reflecting surface upwards.The given convex lens is placed over the plane mirror.The pointer is arranged horizontally on the clamp of the retort stand, vertically above the lens.Looking from above, the height of the pointer is adjusted such that the inverted image of the pointer is obtained.The height is further adjusted so that the image coincides with tip of the pointer without parallax. The image and object will be of the same size.The distance of the pointer from the top (y1) and bottom (y2) of the lens are measured. The average of these values gives the focal length of the f1 of the convex lens.

                                                         

To determine the focal length of the combination of convex lens and liquid lens:Remove the lens and place a few drops of the given liquid on the plane mirror.The lens is then placed over the liquid with its marked face in contact with the liquid.A plano-concave liquid lens is thus formed between the convex lens and the plane mirror.The pointer adjustment for coincidence is done and the distance from the top (y1) and bottom (y2) of the lens are measured.The average of the two values gives the focal length of the combination, F.

                                                                      

Then calculate the focal length of the liquid lens using the formula,                                              
To determine the radii of curvature of the lens:The convex lens is floated in mercury and taken in a china dish with its marked face in contact with mercury.The pointer adjustment for coincidence is done and the distance from the top, d1  of the lens is measured.The distance d of the pointer from the centre of the lens is calculated using the formula,

                                                                  

Where y2 - y1 is the thickness of the lens.Then calculate the radius of curvature of the lens using the formula,

                                                                                 

So the refractive index of the given liquid can be calculated used using the formula,

                                                                                        

Answer 2

If you want to Measure the refractive index of water using concave mirror , then numerous processes are there to observe the index .

First of all In a laboratory, the method which you will have to choose to measure , the refractive index of a liquid process , which depends on different factors .

The factors are optical properties of the substance . So now by a simple geometrical process we can measure it . This is mainy derived from Snell’s law . On the other hand we have to use Gaussian optics equations and thin-lenses for the mirror .