Question

The direction in a uniaxial crystal along which the e-ray and o-ray travel with same speed is:

• A. Brewster angle
• B. Optic axis
• C. Plane of polarization
• D. Angle of polarization

Hint:

In a uniaxial crystal, along the optic axis, ordinary and extraordinary rays travel with the same speed.

Answer 1

The Correct Option is B

Concept:
In a uniaxial crystal, light generally splits into ordinary ray and extraordinary ray due to double refraction.

Step 1: Understand ordinary and extraordinary rays.
The ordinary ray and extraordinary ray usually travel with different velocities in anisotropic crystals.

Step 2: Identify special direction.
In a uniaxial crystal, there is one special direction along which ordinary and extraordinary rays travel with the same speed. This direction is called the optic axis. \[ \text{o-ray speed}=\text{e-ray speed along optic axis} \]

Step 3: Final answer.
Thus, the required direction is: \[ \text{Optic axis} \] \[ \therefore \text{Correct Answer is (B)} \]