A thick plane mirror shows a number of images of the filament of an electric bulb. Of these, the brightest image is the

Options

A. `1^(st)`
B. `2^(nd)`
C. `3^(rd)`
D. `4^(th)`

Answer

To solve the problem of determining which image of the filament of an electric bulb is the brightest when viewed in a thick plane mirror, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Setup**:
- We have a thick plane mirror and a filament of an electric bulb. The mirror reflects light, and due to its thickness, it can create multiple images of the filament.

2. **Formation of Images**:
- When light from the filament strikes the mirror, it reflects off the surface. The first image is formed by the direct reflection of the filament.
- Additionally, some light may enter the mirror and reflect off the inner surfaces of the mirror, creating subsequent images.

3. **Identifying Image Brightness**:
- The brightness of an image is related to the intensity of light that reaches the observer's eye. The first image (direct reflection) will have the highest intensity because all the light is reflected directly from the surface of the mirror.
- The subsequent images formed by internal reflections will have lower intensity due to partial absorption and scattering of light within the mirror material.

4. **Conclusion on Brightness**:
- Since the first image is formed by direct reflection, it retains the maximum intensity of the light from the filament. The other images, formed by internal reflections, will be dimmer.
- Therefore, the brightest image of the filament will be the first image formed by the direct reflection from the surface of the thick plane mirror.

### Final Answer:
The brightest image of the filament of the electric bulb is the **first image** formed by direct reflection from the thick plane mirror.

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