Five spherical mirrors are made from the same sphere. The uncommon thing among the mirrors is _______

Options

A. radius of curvature
B. focal length
C. pole
D. None of these

Explanation

To solve the question, "Five spherical mirrors are made from the same sphere. The uncommon thing among the mirrors is _______", we can follow these steps:

### Step 1: Understand the Components of Spherical Mirrors
Spherical mirrors can be either concave or convex and are formed by cutting a sphere. Each mirror has specific characteristics including radius of curvature, focal length, and pole.

### Step 2: Identify the Radius of Curvature
The radius of curvature (R) is defined as the radius of the sphere from which the mirror is made. Since all five mirrors are made from the same sphere, they will all share the same radius of curvature. Therefore, the radius of curvature is common among all mirrors.

### Step 3: Determine the Focal Length
The focal length (f) of a spherical mirror is related to its radius of curvature by the formula:
\[ f = \frac{R}{2} \]
Since the radius of curvature is the same for all mirrors, the focal length will also be the same for all five mirrors. Thus, the focal length is also common among all mirrors.

### Step 4: Understand the Concept of the Pole
The pole of a spherical mirror is the central point of the mirror's aperture. Since each mirror is cut from different parts of the sphere, the position of the pole will vary for each mirror. Therefore, the poles of the five mirrors will be different.

### Step 5: Conclusion
From the analysis, we find that the radius of curvature and focal length are common among the mirrors, while the poles are different. Thus, the uncommon thing among the mirrors is the pole.

### Final Answer
The uncommon thing among the mirrors is the **pole**.

---