A plane glass slab is kept over colored letters, the letter which appears least raised is

 

 

A) Blue B) Red C) Green D) Violet

Please explain what all the letters in the formulas are.

Red letters means distance and Black letters means angles

Calculate the magnitude and the angle.
A) Vectors: A + B
Vectors: A - B
Vectors: - A - B
Vectors: B - A

Explain the procedure please..

Lets say you've a crystal ball, on one side we cast coloredglass. For which refractive index, the image of crystal grain wouldappear in infinity, when you look from the other side (not colored)of the crystal ball?