Physics Project

To find refractive indices of water and oil

-Muneeb Pasha XIIB

PHYSICSINVESTIGATORY PROJECT

It is my proud privelage to offer my sincere thanks to the Central Board of Secondary Education who has given me this opportunityto make a project on this subject successfully. i would like to offer my sincere thanks and gratitude to Madam Meera Nair, the principal of my school for giving me the golden oportunity to do this project. I am extremely indebted to our Physics teacher Mrs. Neetu Sofat for her able guidance, timely help and constructive encouragement towards the completion of this project. And at last, i would like to offer my sincere thanks to our lab assisstant for guiding me on a step to step basis and ensuring that i completed all my experiments with ease.

Acknowledgement

Bibliography

Sources of Error

Precautions

Results

Calculations

Obervations

Procedure

Theory

Aim and Apparatus

Introduction

-------------------------------------------------------------------------------------------

-------------------------------------------------------------------------------------------

INDEX

Refractive index is also equal to the velocity of light c of a given wavelength in empty space divided by its velocity v in a substance;

-------------------------------------------------------------------------------------------

Introduction

In optics, the refractive index or index of refraction n of a material is a dimensionless quantity that describes how light propagates through that medium. If i is the angle of incidence of a ray in vacuum (angle between the incoming ray and the perpendicular to the surface of a medium, called the normal) and r is the angle of refraction (angle between the ray in the medium and the normal), the refractive index n is defined as the ratio of the sine of the angle of incidence to the sine of the angle of refraction;

_____________________________________________

____________________________________________

_____________________________________________

____________________________________________________________

To find the refractive indices of a) Water and b) Oil (Transparent) using a plane mirror, an equiconvex lens (made from a glass of known refractive index) and an adjustable object needle.

AIM

Spherometer

Glass Slab

Half Metre Scale

Knitting Needle

Plumb Line

An Optical Needle

Clamp Stand

Oil

Water

Plane Mirror

A Convex Lens

Apparatus

Inserting values of f2, n can be calculated.

Liquid lens formed is a Plano-concave lens with R1=R (radius of curvature of convex lens surface), R2=♾️. From the lens maker’s formula We have,

Let us consider f1 and f2 to be the focal length of the glass convex lens and liquid lens respectively and let F be the focal length of their combination, then :

Let us consider f1 and f2 to be the focal length of the glass convex lens and liquid lens respectively and let F be the focal length of their combination, then :

Theory

Diagram

9.) Take the mean of the two readings. This means distance will be equal to the focal length of the convex lens.

----------------

8.) Also, measure the distance between the tip and the surface of its plane mirror.

----------------

7.) Measure the distance between the tip and upper surface of the lens using a plumb line and half metre scale.

----------------

6.) Move the needle up and down and remove the parallax between the tips of the needle and its image.

----------------

5.) Bring the tip of the needle to the principal vertical axis of the lens so the tip of the needle appears to be touching the tip of its image.

----------------

4.) Screw tight the optical needle in the clamp of the stand and hold it horizontally above the lens at a distance equal to its rough focal length.

----------------

3.) Place the convex lens on the plane mirror.

----------------

2.) Place the plane mirror on the horizontal base of the iron stand.

----------------

1.) Choose a convex lens and find its rough focal length.

-------------------------------------------------------------------------------------------

a.) For focal length of convex lens

Procedure

----------------

17.) Remove the spherometer from the surface of the lens and place on the plane mirror surface and record the reading.

----------------

18.) Repeat the steps

----------------

17.) Remove the spherometer from the surface of the lens and place on the plane mirror surface and record the reading.

----------------

14.) Determine the pitch and the least count of spherometer.

----------------

c.) For radius of curvature of convex lens

13.) Repeat steps 10, 11 and 12 for oil.

----------------

15.) Remove the convex lens and dry it completely. Put the spherometer on this lens surface.

----------------

12.) Record the observation.

----------------

11.) Repeat steps 5, 6, 7, 8 and 9 to determine the equivalent focal length of the combination.

----------------

16.) All the three legs of the spherometer should be placed symmetrically on the lens and adjust the central screw tip to touch the surface of the lens.

----------------

10.) Put a few drops of the water on the plane mirror and put the convex lens over it with its same face above as before. The water spreads in a form of layer and acts like a plano-concave lens.

-------------------------------------------------------------------------------------------

b.) For focal length of the combination

----------------

To measure focal length ‘f’ of convex lens

Table for calculation of ‘h’

CA = 3 cm

BC = 3 cm

AB = 3 cm

Distance between the legs:

Least Count of the Spherometer = 0.01 cm

Pitch of the spherometer = 1 cm

Observations

-----

With water between the convex lens and the plane mirror:

-----

With water between the convex lens and the plane mirror:

Measurement of refractive indices of water and oil

To find the radius of curvature of the convex lens:

Mean of h =

Mean distance between two legs:

Calculations

The tip of the central screw should not just touch the surface of lens or mirror.

The spherometer legs should be placed symmetrical on the surface of the convex lens.

The parallax may not be fully removed.

Liquid my not be quite transparent.

Sources of Error

The legs of the spherometer should be vertical.

The centre leg of the spherometer should turn in one direction only.

Only few drops of liquid should be taken so that its layer should be thick.

The eye should be at a distance about 30 cm from the needle while removing parallax.

The parallax should be removed tip to tip.

The liquid taken should be transparent.

The plane mirror should be clean and fully shining surface.

Precautions

The refractive index of oil is μ2 = 1.2886

The refractive index of water is μ1 = 1.0831

-------------------------------------------------------------------------------------------

Results

_____________________________________________

____________________________________________

_____________________________________________

____________________________________________________________

NCERT class 12 Physics textbook

WWW.academia.edu

WWW.coursehero.com

WWW.slideshare.net

WWW.Byjus.com

WWW.Wikipedia.com

Bibliography