Refractive Indices of Water And Turpentine Oil Essay Example

from the Centre of the upper surface of the lens. Let it be ten 1. ( Use plumb line ) .
• Remove the convex lens and step the distance of the tip of the acerate leaf from the plane mirror. Let it be ten 2. ( Use plumb line ) . 2 ( six ) Repeat and record all the observations.
• For happening the focal length of the plano-concave lens: Pour few beads of H2O over the plane mirror and topographic point the convex lens over it. Repeat stairss ( two ) to ( four ) as done above. Repeat the process with turpentine oil besides.
• For happening ‘l’ :

Determine the pitch and least count of graduated table of the spherometer. Put the spherometer on the dried surface of the convex lens. Turn the prison guard downwards really gently till the tip of the prison guard merely touches the lens. Read and enter the reading. Keep the spherometer’s legs on the base of a paper and seting the cardinal prison guard. happen the assholes A. B and C of the three legs of the spherometer. Join the Centres of the three assholes and step the lengths with the half-metre graduated table. Note the values of AB. BC and AC

Decision

Pitch of the spherometer= 1 centimeter
Least count of the spherometer = 0. 01 centimeter
Distance between the legs:
• AB = 3 centimeter
• BC = 3 centimeter
CA = 3 centimeter
S. No
Initial reading of the C. S. on the convex lens
( a )
No. of complete rotary motions

( N )
Concluding reading of the c. s on the glass slab
Additional C. S div. moved
h=n x pitch + m x L. C
Mean “h”
1
62
0
6.

5
55. 5
0. 555
0. 5775
2
64
0
4
60
0. 6

Aim is to happen the refractile index of a ) H2O. B ) coconut oil utilizing a plane mirror. and an equiconvex lens made of glass and an adjustable object acerate leaf. The theory behind liquid lens is based on the belongingss of one or more liquids to make magnifications within a little sum of infinite. The focal point of a liquid lens is controlled by the surface of the liquid. Water usually forms a bubble form when adhered to stuffs such as glass. This desirable belongings makes H2O a really suited campaigner for the production of liquid lens. Basically the liquid must be crystalline so as to analyze its effects. To bring forth a liquid lens. a liquid is sandwiched between two pieces of a clear plastic or a glass. Oil ( needfully transparent ) can besides be chosen to be used as a fluid in a liquid lens system. The surface profiles of the liquid determines the focal length of liquid lens system and how the liquid lens focal points light beams.

Theory:

In optics. refractile index or index of refraction ‘n’ of a substance ( optical medium ) is a dimensionless figure that describes how light or any radiation propagates through that medium. It is defined as n = c/v

where’ c’ is the velocity of visible radiation in vaccum and ‘v’ is the velocity of visible radiation in a substance. Eg: ‘n’ of H2O is 1. 33. which means. light travels 1. 33 times as fast in vaccum as it does in H2O. The historically first occurance of refractile index was in Snell’s jurisprudence of refraction. Internet Explorer are the

angles of incidence of the beam traversing the interface between 2 medias with refractile indeces n_1 and n_2. In this undertaking. we shall do usage of the belongings of liquid lens to happen the refractile index of H2O and coconut oil.

Requirements

A convex lens. plane mirror. H2O. coconut oil. an optical acerate leaf. an Fe base with base and clinch agreement. a metre graduated table etc… . Procedure:
• Finding the focal length of convex lens: -
• Place the plane mirror with the convex lens placed on it above the horizontal base of a clinch base horizontally as its tip lies vertically above the ocular Centre of the lens. Adjust the acerate leaf at a tallness a little more than the unsmooth focal length of the convex lens.
• Bring the tip of the acerate leaf. at the perpendicular chief axis of the lens. so that the tip of the needle appears touching the tip of its image.
• Move the acerate leaf up and down to take the parallax between tips of needle and its image.
• Measure the distance between tip of the needle and upper surface of the lens by utilizing a metre graduated table. Let it be ( x1 ) .
• Again step the distance between tip and upper surface of the plane mirror. Let it be x2
• Finding the focal length of the combination:
• Take a few beads of the given transparent liquid and topographic point it on the surface of plane mirror. The convex lens is placed over it as earlier. ( A Plano concave lens is formed between plane mirror and convex lens ) .
• Repeat the stairss ( two ) to (

V )
• Record the observations.
• To happen the radius of curvature of the liquid lens. ( R of convex lens surface in contact ) . The convex lens is turned towards a beginning such that. the needed surface is off from the beginning the distance is to set that the image is. formed on the side of the beginning. The distance ‘d’ between the beginning and the lens is measured.

The radius of curvature ‘R’ of the lens is given by

Finally the refractile index of liquid lens is given by.
n = 1+ R/f2
Consequence:
The observations of the experiment is tabulated as follows

Precautions
• The parallax must be removed tip to tip decently.
• The lens and plane mirror should be cleaned thouroughly.
• The liquid taken should be basically crystalline.
Merely few beads of liquid should be taken so that the liquid lens bed is non thick

Beginnings of mistake:
• Liquid may non be rather crystalline
• The parallax any non be to the full removed
• The acerate leaf may non be decently horizontal
The distance x1 and x2 may non be basically clean

The experiment described in this undertaking is an effectual and simple method of mensurating the refractile index of any liquid ( transparent ) utilizing a convex lens and plane mirror. If we keep the mirror behind a lens and put an object at the focal point point of the lens above it. the image of the object will organize at the same focal point point where the object is. If it is an drawn-out object. its image will be inverted and the size of image is same as that of the object. This belongings has enabled the efficient usage of liquid

lens to happen the refractile index of a fluid by this method. If a liquid is sandwiched between the lens and the mirror. the focal length of liquid lens can be calculated cognizing the focal length of the combination and that of the convex lens. from which the refractile index of the fluid can easy be estimated.