When Light in Medium 1 Is Reflected from the Surface

Multiple Choice

When light in medium 1 is reflected from the surface of medium 2 with the indices of refraction of the media being n₁ and n₂ respectively, the reflected light has a phase difference of 180° if

A) n₁ > 3 n₂.
B) n₁ = n₂.
C) n₁ < n₂.
D) n₁ > n₂.
E) n₁ > 2 n₂.