Question

If a light beam (solid arrow in the shown figure) is entering from Air medium to Glass medium (having refractive index of \(1.5\)), then while entering

• A. speed of light will decrease
• B. speed of light will increase
• C. light will bend (deviate from original path) if \(\theta \neq 0\)
• D. light will undergo total internal reflection

Hint:

When light enters a denser medium, its speed decreases and it bends toward the normal. Total internal reflection occurs only from denser to rarer medium.

Answer 1

The Correct Option is A, C

Step 1: Name the media.
Light passes from air into glass of refractive index $1.5$. Glass is the denser medium of the two.

Step 2: Track the speed.
Speed in a medium is $v = c/n$. A bigger $n$ means a slower wave, so the light slows down on entering glass. That makes A true and B false.

Step 3: Track the direction.
If the ray hits at any angle other than straight on, that is $\theta \neq 0$, it bends toward the normal as it enters the denser glass. So statement C is true.

Step 4: Rule out total internal reflection.
Total internal reflection only happens going from dense to rare beyond the critical angle. Here we go rare to dense, so D cannot happen.

Step 5: Answer.
\[ \boxed{A,\ C} \]