Question

If white light is used in the Newton's rings experiment, the colour observed in the reflected light is complementary to that observed in the transmitted light through the same point. This is due to

• A. 90${}^{\circ }$ change of phase in one of the reflected waves
• B. 180${}^{\circ }$ change of phase in one of the reflected waves
• C. 145${}^{\circ }$ change of phase in one of the reflected waves
• D. 45${}^{\circ }$ change of phase in one of the reflected waves

Answer 1

Answer: (B)

The rings observed in reflected light are exactly complementary to those seen in transmitted light. Corresponding to every dark ring in reflected light there is a bright ring in transmitted light. The ray reflected at the upper surface of the air-film suffers no phase change while the ray reflected internally at the lower surface suffers a phase change of $\pi$