Changing the Speed of Light

by | Sep 28, 2022 | Physics, Experiments

Introduction

In this experiment(Changing the Speed of Light), we will be determining the refractive index of different materials using air as the constant medium and also comparing these refractive indexes.

For performing this experiment, we constructed an apparatus to measure light passing through the medium, demonstrating the principle of light propagation. We have designed the apparatus in such a way that refracted light could use the full length of the apparatus and yield an accurate temperature.

This apparatus will also minimize the volume of each fluid to less than one gallon for each test.

Aim

To determine the refractive index of different materials and also compare them.

Theory

1. Refractive index of a material defines how fast light has travelled through that medium.

2. It is a dimensionless quantity.

3. The formula for refractive index is n = c/v. Where n is the refractive index, c is the speed of light, and v is the phase velocity of light.

M

Requirements

1. A laser,

2. A tank field with water,

3. Laser holder,

4. Corn oil,

5. Ruler,

6. Glass cleaner,

7. Tape,

8. Notebook.

9. Olive oil,

10. Palm oil,

11. Canola oil.

Procedure

Step 1: Use a small laser requiring less than 3V as a light source.

Step 2: Place this laser on a laser holder made from wood scrap.

Step 3; Direct this laser light on the air/liquid interface.

Step 4: After falling, the beam will split into two rays, one that gets reflected after hitting the interface and the other that gets refracted into the liquid medium to the bottom of the tank.

Step 5: Measure the adjacent side and opposite side of two triangles that have been created.

Step 6: Calculate the angle of the refraction using this measurement and trigonometry.

Step 7: Repeat this experiment using different kinds of liquid.

Step 8: Record your observations.

Observation

1. We observed that our constructed apparatus can accurately measure the refractive index for a one-gallon sample.

2. The refractive index of the liquid is related to its density.

3. In some fluids it was easier to see laser light.

4. Refractive index does not change its value on changing the incident angle of the light beam.

5. We also observed different phenomena related to fluid, for instance, scattering of light, density and viscosity of the fluid.

Result

From all the oils we tested for this experiment, corn oil proved to have the highest refractive index due to the reason of having the highest fluid density.

Precaution

1. Tank should be constructed from glass.

2. Use a silicone sealer to seal the side of the tank.

3. Record your observation precisely.

Conclusion

This experiment is being conducted to measure the refractive index of different oils.

Viva Questions with Answers

Q.1 What was the aim of your experiment?

ANS. To determine the refractive index of different materials and also compare them.

Q.2 Which oil had the largest refractive index?

ANS. Corn oil had the largest refractive index.

Q.3 What is the relation between refractive index and density?

ANS. The refractive index of a medium is directly dependent on the density of that medium. This means on increasing density, the refractive index increases.

Q.4 What is the refractive index of corn oil?

ANS. Between 1.470 and 1.471

 

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