Determination of the Refractive Index

Introduction

• The refractive index (or index of refraction) of a material indicates how much light slows down when it passes through the material.
• To determine the refractive index of a medium, we can perform an experiment involving the use of a semi-circular block.

Equipment and Setup

• Semi-Circular Block: Begin with a semi-circular block of the material whose refractive index you want to determine.
• Normal Line: Draw a dashed normal line at 90 degrees to the midpoint of the straight edge of the semi-circular block.
• Raybox: Set up a raybox to emit a ray of light.
• Incident Ray: Direct the incident ray at an angle of incidence (angle between the incident ray and the normal) of 10 degrees to the normal line.
• Mark Refracted Ray: Mark the refracted ray by placing two pencil crosses where it intersects.
• Measurement: Remove the raybox and semi-circular block, then measure the angles of incidence and refraction from the normal using a protractor.
• Repeat Measurements: Repeat this process for various angles of incidence ranging from 15 to 40 degrees.
• Data Collection: Record the corresponding values of the sine of the angle of incidence and the sine of the angle of refraction for each measurement.

Data Analysis

• Graph Plotting: Plot a graph with the sine of the angle of incidence on the y-axis and the sine of the angle of refraction on the x-axis.
• Gradient Calculation: Calculate the gradient of this graph. The gradient represents the refractive index of the material of the semi-circular block.

Summary

• The refractive index of a material measures how much light is slowed down when it passes through the material.
• To determine the refractive index of a medium, an experiment involving a semi-circular block is conducted.