Physics 3.2.3 Refraction at a Plane Surface

12 flashcards · Physics · by TheoTyson

1. What is the refractive index of a material?

   The measure of how much a material slows down light, the optical density of the material.

2. How is light refracted when it enters an optically denser medium?

   It is refracted towards the normal.

3. What is the angle of incidence?

   The angle the incoming light makes to the normal.

4. What is the angle of refraction?

   The angle the refracted ray makes to the normal.

5. What is the refractive index of a substance?

   n=ccsn = \frac{c}{c_s}n=cs​c​

6. What is Snell's Law?

   n1sin⁡θ1=n2sin⁡θ2n_1 \sin{\theta_1} = n_2 \sin{\theta_2}n1​sinθ1​=n2​sinθ2​

7. What is the formula for critical angle?

   sin⁡θc=n2n1\sin{\theta_c} = \frac{n_2}{n_1}sinθc​=n1​n2​​

8. What are the two criteria for total internal reflection?

   n1n_1n1​ is greater than n2n_2n2​ , and the angle of incidence is greater than the critical angle.

9. What happens when the angle of incidence is greater than the critical angle?

   All of the light is reflected back.

10. What happens in an optical fibre?

    The high refractive index fibres are surrounded by low refractive index cladding to ensure total internal reflection.

11. What is material dispersion?

    The input light consists of different wavelengths travelling at different speeds and so they reach the end at different times.

12. What is modal dispersion?

    The input light rays enter at different angles and so take different paths, some paths are shorter so those rays arrive sooner.