Refraction of Light

Introduction

What is Refraction of light?

The bending of light as it passes from one medium to another is called refraction.

The angle and wavelength at which the light enters a substance and the density of that substance determine how much the light is refracted

When light passes from a more dense to a less dense substance, (for example passing from water into air), the light is refracted (or bent) away from the normal.

How much does light bend?

The bending of a light as it crosses boundary into a different medium is determined by its reflective index, or how much the light slowed down in the new medium.

Table shows the refractive indices of some common materials

Material
Air (STP)	1.00029
Water	1.33
Ice	1.31
Glass:
Light flint	1.58
Heavy flint	1.65
Heaviest flint	1.89
Diamond	2.42

Law of Refraction

Consider a light-ray incident on a plane interface between two transparent dielectric media, labelled First and Second, as shown in picture given The law of refraction states that the incident ray, the refracted ray, and the normal to the interface, all lie in the same plane. Furthermore,

$\begin{displaymath}<br /> n_1\,\sin\theta_1 = n_2\,\sin\theta_2,<br /> \end{displaymath}$

Where $\theta_1$ is the angle subtended between the incident ray and the normal to the interface, and $\theta_2$ is the angle subtended between the refracted ray and the normal to the interface. The quantities and are termed the refractive indices of media 1 and 2, respectively. Thus, the law of refraction predicts that a light-ray always deviates more towards the normal in the optically denser medium: i.e., the medium with the higher refractive index. Note that in the figure.

Task

1. Define refraction of light.

2. Why does the light refract when it enters water from air?

3.Define index of refraction.

4. What do you call a light ray that is in the first medium?

5. What do you call a light ray that is in the second medium?

6. What is the normal line?

7.What is the formula that is used to calculate the incedent ray?

8. If the incedent angle is 30 degrees but the reflected angle is 22,8 degrees then what is the second reflective index if the first is reflective index is 1?

9. If the first reflective index is 1 and the second reflective index is 1,58 then what how big is the incident angle if the reflected angle is 63 degrees.

10. Light enters water from air how big is the reflected angle if the incedent angle is 40?

Process

1. Read the introduction

2. Read these articles if needed to reflect on the intoduction:

Refraction of light

Law of refraction

3. Watch these videos to understand the guven information even more:

1) What is refraction of light - Optics for kids

2) Refraction & Dispersion: Definition, Snell's Law & Index of Refraction

4. Do the given tasks and check evaluation to find out the answers

Evaluation

Evaluation for the tasks and answers:

1. The change in diraction of a wave when passed from 1 medium to another ( 2p)

2. Water is more dense than air (2p)

3. Index of refraction is how a medium refracs a light (2p)

4. Incedent ray (1p)

5. Reflected ray (1p)

6. Imagenary line that is perpendicular to the surface (2p)

7. $\begin{displaymath}<br /> n_1\,\sin\theta_1 = n_2\,\sin\theta_2,<br /> \end{displaymath}$ (1p)

8. 1,31 (2p)

9. 84 degrees (2p)

10. 28,8 degrees (3p)

In total: 18p

Conclusion

Congratulations! You have completed the Refraction of Light webquest. This is a brief and easy introduction into the light of refraction. You have learned how and why does the light refract.