______is also used in instruments such as periscopes and kaleidoscopes,

Options

A. Spherical mirror
B. Plane mirror
C. Polished mirror
D. Multiple reflection

Answer

To answer the question, we need to identify what is used in instruments such as periscopes and kaleidoscopes.

### Step-by-Step Solution:

1. **Understanding the Instruments**:
- A **periscope** is an optical instrument that allows the user to see objects that are not in their direct line of sight. It typically consists of two mirrors set at 45-degree angles.
- A **kaleidoscope** is an optical device that creates beautiful patterns through the reflection of light. It usually contains three mirrors arranged in a triangular formation.

2. **Identifying the Components**:
- Both instruments rely on the principle of reflection to function.
- In a periscope, light reflects off the two mirrors, allowing the viewer to see an image from above or around an obstacle.
- In a kaleidoscope, light reflects off multiple mirrors, creating intricate patterns.

3. **Determining the Type of Mirror Used**:
- In both instruments, **plane mirrors** are used.
- Plane mirrors are flat surfaces that reflect light without distorting the image, which is essential for both the periscope and the kaleidoscope.

4. **Conclusion**:
- Therefore, the answer to the question is: **Plane mirrors** are used in instruments such as periscopes and kaleidoscopes.

### Final Answer:
**Plane mirrors** are also used in instruments such as periscopes and kaleidoscopes.

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