When a light ray enters from one optical medium to another and bends towards the normal then,

Options

A. Angle of incidence is less than angle of refraction
B. it is travelling from optically denser medium to optically rarer medium
C. it is travelling from optically rarer medium to a optically denser medium
D. Speed of light remains unchanged

Explanation

To solve the question, we need to analyze the behavior of light as it transitions between two different optical media. Here’s a step-by-step solution:

### Step 1: Understand the scenario
When a light ray travels from one optical medium to another and bends towards the normal, it indicates that the light is entering a medium with a higher refractive index.

**Hint:** Remember that the normal line is an imaginary line perpendicular to the surface at the point of incidence.

### Step 2: Define the angles
Let:
- θ₁ = angle of incidence (the angle between the incoming ray and the normal)
- θ₂ = angle of refraction (the angle between the refracted ray and the normal)

Since the light ray bends towards the normal, we can conclude that θ₂ < θ₁.

**Hint:** Visualize the angles with a diagram to see how they relate to the normal.

### Step 3: Apply Snell's Law
According to Snell's Law, the relationship between the angles and the refractive indices of the two media is given by:
\[ n_1 \sin(θ_1) = n_2 \sin(θ_2) \]
Where:
- n₁ = refractive index of the first medium
- n₂ = refractive index of the second medium

Since θ₂ < θ₁, it follows that:
\[ \sin(θ_2) < \sin(θ_1) \]
This implies that n₂ must be greater than n₁ (i.e., n₂ > n₁).

**Hint:** Remember that the sine function increases with the angle; thus, a smaller angle corresponds to a smaller sine value.

### Step 4: Determine the nature of the media
Since the light ray is bending towards the normal, it is moving from an optically rarer medium (lower refractive index) to an optically denser medium (higher refractive index).

**Hint:** Think of "rarer" and "denser" in terms of how much light slows down in each medium.

### Step 5: Analyze the speed of light
When light travels from a rarer medium to a denser medium, its speed decreases. Therefore, the speed of light in the second medium (denser) is less than in the first medium (rarer).

**Hint:** Recall that the speed of light is inversely related to the refractive index; a higher refractive index means a lower speed.

### Conclusion
From the analysis:
- The correct conclusion is that the light ray is moving from an optically rarer medium to an optically denser medium, which means n₂ > n₁.
- The speed of light decreases when moving from a rarer to a denser medium.

**Final Answer:** The light ray is traveling from an optically rarer medium to an optically denser medium, and its speed decreases.