Ans:
Ordinary rays
1) The ray's which obeys Snell's law and laws of refraction is called ordinary ray.
2) It is denoted by O.
3) It passes undeviated through the crystal.
4) Inside the crystal, speed of O-ray is less than E-ray.
5) The speed is constant in the medium.
6) It gives spherical wavefront.
Extra ordinary ray
1) The ray which does not obey the laws of refraction is called extra ordinary ray.
2) It is denoted by E.
3) It deviates after refraction.
4) Inside the crystal, speed of E-ray is more than O-ray.
5) The speed is not constant in the medium.
6) It gives ellipsoidal wavefront.
