Under which condition will a light wave incident from air experience a 180° phase change upon reflection?
a) 180∘ phase shift occurs whenever light reflects, regardless of the two media.
b) When light reflects from a boundary where the second medium has a higher refractive index than the incident medium.
c) When light reflects from a boundary where the second medium has a lower refractive index than the incident medium.
d) Only if the angle of incidence exceeds the critical angle, i.e. during total internal reflection.