Question

Assertion (A) : Small glass beads fixed on traffic signals glow brightly when light falls upon them. 

Reason (R) : Light is totally reflected when the angle of incidence exceeds a certain critical value and light travelling in a denser medium is reflected from a rarer medium. 

Codes : 

(a) Both A and R are true and R is the correct explanation of A 

(b) Both A and R are true but R is not a correct explanation of A

 (c) A is true but R is false 

(d) A is false but R is true

Answer 1

(a) Both of the statements are correct and statement 2 is also correct explanation for statement 1. Total internal reflection is an optical phenomenon that happens when a ray of light strikes a medium boundary at an angle larger than a particular critical angle with respect to the normal to the surface. If the refractive index is lower on the other side of the boundary, no light can pass through and all of the light is reflected. Thus because of this phenomena traffic light beads glow when light falls on them.