a light ray is incident normally on a plane mirror.
a. What is its angle of incidence?
b. What is the direction of reflected ray? Show it on a diagram.

Answer

To solve the question regarding the light ray incident normally on a plane mirror, let's break it down step by step.

### Step 1: Understanding the Angle of Incidence
When a light ray hits a surface, the angle of incidence is defined as the angle between the incident ray and the normal (an imaginary line perpendicular to the surface at the point of incidence).

Since the light ray is incident normally on the plane mirror, it means that it strikes the mirror at a right angle.

**Solution:**
a. The angle of incidence is 0 degrees.

### Step 2: Understanding the Reflection of Light
According to the law of reflection, the angle of reflection is equal to the angle of incidence. Since the angle of incidence is 0 degrees, the angle of reflection will also be 0 degrees.

**Solution:**
b. The direction of the reflected ray will be the same as the direction of the incident ray.

### Step 3: Diagram Representation
To illustrate this, we can draw a simple diagram:

1. Draw a horizontal line to represent the plane mirror.
2. Draw a vertical dashed line perpendicular to the mirror to represent the normal.
3. Draw an arrow pointing towards the mirror to represent the incident ray, starting from the left and hitting the mirror at the normal.
4. Draw another arrow pointing away from the mirror on the same line as the incident ray to represent the reflected ray.

Here’s a simple representation:

```
|
| Incident Ray
| ----->
|
-------|-------
| Reflected Ray
| <-----
```

### Final Answers:
a. The angle of incidence is 0 degrees.
b. The direction of the reflected ray is the same as the incident ray.

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