CERTIFICATE
This is certified that Mr. AMIT SARKAR has successfully completed his
physics project on titled “Refractive index and passing through at in water.”
Under the supervision and guidance of Mr./Mrs. Teacher name in the partial
fulfillment of the physics practical. Assessment conducted during the academic
year 2024 -2025.
EXAMINER TEACHER
…………….. ..……….
AKONWLEDGEMENT
I would like to express my immense gratitude to my physics teacher
Mr./Mrs. Teacher name the help and guidance of he/she for completing this
project.
I also thank my parents who gave me their idea and input in making this
project. Most of all I thank our school management for providing us
with the facilities and opportunity to do this project.
Lastly, I would like to thank my classmate who did this project along
with me. Their support made this project fruitful.
Mr. Amit sarkar
(roll no)
Class 12
INDEX
CONTENT PAGE NO
CERTIFICATE
Acknowledgement
Topic
Introduction
Aim
TOPIC
Refractive index and passing through at in water.
INTRODUCTION
Refractive Index (n): The refractive index of a medium is a measure of how
much light slows down as it passes through that medium compared to its speed
in a vacuum. It is defined as:
n=c/v (n = fraction of {c},{v})
Where:
c is the speed of light in a vacuum (approximately 3×1083 \times 10^8
meters per second).
V is the speed of light in the medium.
For water, the refractive index n is typically around 1.33. This means that light
travels about 1.33 times slower in water than it does in a vacuum.
Behavior of Light Passing Through Water
When light passes from one medium to another (e.g., from air to water), its
speed and direction change, a phenomenon known as refraction.
Snell's Law governs the refraction of light and is given by:
n1sin(θ1) = n2sin(θ2)
Where:
n1 is the refractive index of the first medium (e.g., air, which has n≈1).
n2 is the refractive index of the second medium (e.g., water, with n≈1.33).
θ1 is the angle of incidence (the angle between the incident light ray and
the normal to the surface).
θ2 is the angle of refraction (the angle between the refracted light ray and
the normal to the surface).
AIM OF THE PROJECT
To find the direction of light when it passes from air into water.
APPARATUS REQUIRED
1. Laser Pointer or Light Source: To emit a narrow beam of light for
precise measurements.
2. Glass Tank or Container: A transparent container filled with water to
observe the refraction of light.
3. Protractor: To measure the angles of incidence and refraction accurately.
4. Ruler or Measuring Tape: To measure distances and ensure proper
alignment of the light source.
5. Graph Paper: To record measurements and plot the path of the light
beam.
6. Pen and Notebook: To note down observations and calculations.
7.
Calculator: For performing calculations using Snell's Law.
PROCEDURE
Procedure to Determine the Refractive Index of Water
Steps:
1. Setup:
o Place the glass tank filled with water on a stable, flat surface.
o Ensure the water surface is calm.
2. Align Light Source:
o Position the laser pointer so the beam strikes the water surface at a
known angle.
o Use the protractor to measure this angle of incidence (θ1).
3. Measure Angle of Incidence:
o Shine the laser beam onto the water surface.
o Record the angle of incidence (θ1) using the protractor.
4. Measure Angle of Refraction:
o Observe the light bending as it enters the water.
o Use the protractor to measure the angle of refraction (θ 2), which is
the angle inside the water.
5. Calculate Refractive Index:
o Use Snell's Law: n1sin(θ1) = n2sin(θ2)
o Given n1 (refractive index of air) ≈ 1:
o Calculate the refractive index of water (n2):
o n2 =: n1sin(θ1)/ sin(θ2)
6. Repeat for Accuracy:
o Perform multiple trials with different angles of incidence.
o Average the results for a more accurate measurement.
