Q-If Fast ray vibrating along the length of Tetragonal and Hexagonal Crystals, then the Crystals will be ? a- Biaxial + b- Biaxial c-Uniaxial+ d-Uniaxial
Correct option most probably will be (D).
The optic sign of the crystal in given orientation is negative (Uniaxial -ve) .
I've attached figure for better understanding and to hav...