`v_(O)` and `v_(E)` represent the velocities, `mu_(O) and mu_(E)` the refractive indices of ordinary and extraordinary rays for a doubly refracting cystal. Then

Options

A. `v_(O) le v_(E),mu_(O) le mu_(E)` if the crystal is quartz
B. `v_(O) ge v_(E),mu_(O) lemu_(E)`, if the crystal is calcite
C. `v_(O) ge v_(E),mu_(O) ge mu_(E)`, if the crystal is quartz
D. `v_(O) le v_(E),mu_(O)gemu_(E)`, if the crystal is calcite

Answer

D

Explanation

If `v_(O) and v_(E)` represents the velocities, `mu_(O) and mu_(E)` the respective indices of ordinary and extraordinary rays for a doubly refracting crystal, then
`(mu_(O))/(mu_(E))=(v_(E))/(v_(O))`
Now, for a quartz crystal (positive crystal)
`mu_(O)lemu_(E) thereforev_(O)gev_(E)`.
ad for a calcite crystal (negative crystal)
`mu_(O) ge mu_(E) thereforev_(O)lev_(E)`.