When a ray of light from air enters a denser medium, it :

Options

A. bends away from the normal
B. bends towards the normal
C. goes undeviated
D. is reflected back

Answer

To solve the question "When a ray of light from air enters a denser medium, it:", we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Mediums**:
- We have two mediums: air (which is a rarer medium) and a denser medium (like glass or water).

2. **Understand the Incident Ray**:
- A ray of light travels from air and strikes the boundary of the denser medium at an angle.

3. **Apply the Law of Refraction**:
- According to Snell's Law, when light travels from a rarer medium (air) to a denser medium, it bends towards the normal line (an imaginary line perpendicular to the surface at the point of incidence).

4. **Direction of Bending**:
- As the light enters the denser medium, it slows down. This decrease in speed causes the light ray to bend towards the normal.

5. **Refractive Index Consideration**:
- The refractive index of air (n_a) is less than that of the denser medium (n_d). This means n_d > n_a, which confirms that the speed of light decreases in the denser medium.

6. **Conclusion**:
- Therefore, when a ray of light from air enters a denser medium, it bends towards the normal.

### Final Answer:
When a ray of light from air enters a denser medium, it bends towards the normal.

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