Explanation:

- A concave mirror focuses light inward to a single focal point. This property is used to form images.

- The radius of curvature (R) is 50 cm. The focal length (f) is half of this, so \(f = \frac{50}{2} = 25\) cm.

- The object distance (u) is 25 cm. According to the mirror formula \(\frac{1}{f} = \frac{1}{v} + \frac{1}{u}\), substitute the values:

$$

\frac{1}{25} = \frac{1}{v} + \frac{1}{25}

$$

- This simplifies to \(\frac{1}{v} = 0\), suggesting the image distance (v) is at infinity.

- Therefore, the image is formed at infinity when the object is at the focal length.

Option 1: At infinity