Critical Angle Experiment (Total Internal Reflection) - GCSE Required Practical

We will find the critical angle and refractive index of a perspex block by using a ray box and a protractor.

When the angle of incidence is smaller than the critical angle, the ray is refracted.
When the angle of incidence is larger than the critical angle, the ray goes through total internal reflection.
When the angle of incidence is equal to the critical angle, the ray travels along the boundary of the prism. This is the angle of incidence that we want to note down.

To find the refractive index, you need to do 1/sin(C).

Music credit:
Song: Dipcrusher - Islands (Vlog No Copyright Music)
Music provided by Vlog No Copyright Music.

[Zoe-vzjl]

I'm doing OCR alevel physics and you are an utter life saver, thank you 😊

[kajjamakshaykumar]

I understand it very easily thankyou very much😊😊😊

[tchrsab]

Very useful for my online class during pandemic
Tqvm

[devarajdeva]

Pls do it for prism by varying I angle of incidence we can observe deviation

[yousefshello]

Great work, but I have a question, should the critical angle occurs when the reflected light beam is travelling through the boundary and in 90 degrees with the normal, in the amazing video I have noticed 43 degrees was still has some refracted light? Thank you for the great job, keep it up.

[alonzoball]

Great work but i thought in order to find the critical angle, the ray must be refracted at a 90 degree...Can you please explain why it has to reflect internally rather.

[DopamineMVWM]

I'm so annoyed that they didn't demonstrate the critical angle or total internal reflection with the experiment; all that set up for nothing!