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: Understand the media involved.
The light ray is traveling from air to glass. Air is an optically rarer medium, while glass is an optically denser medium with refractive index
\[ n=1.5 \]

Step 2: Recall the relation between speed and refractive index.
The speed of light in a medium is given by
\[ v=\frac{c}{n} \] where
\[ c=\text{speed of light in vacuum} \] and \(n\) is refractive index of the medium.

Step 3: Analyze change in speed.
Since glass has refractive index greater than air, the speed of light decreases on entering glass.
Therefore, option (A) is correct and option (B) is incorrect.

Step 4: Understand refraction of light.
When light enters a different medium at an angle other than normal incidence, its direction changes due to refraction.

Step 5: Analyze the condition \(\theta \neq 0\).
If the angle of incidence
\[ \theta \neq 0, \] the ray bends toward the normal while entering the denser medium.
Hence, option (C) is correct.

Step 6: Analyze total internal reflection.
Total internal reflection occurs only when light travels from a denser medium to a rarer medium at an angle greater than the critical angle.
Here, light travels from air to glass, so total internal reflection cannot occur.
Thus, option (D) is incorrect.

Step 7: Final conclusion.
Therefore, the correct statements are
\[ \boxed{(A)\text{ and }(C)} \]