The correct option is 1 only
Explanation
A plane mirror consists of a flat reflective surface. The characteristics of the image formed are governed by the laws of reflection. The nature, orientation, and size of the image are constant regardless of the object's distance from the mirror.
Statement-wise Analysis:
- Statement 1 is Correct. The image formed by a plane mirror is always virtual and erect. It is virtual because the light rays do not actually meet at the image point but appear to diverge from it behind the mirror. It is erect because the image maintains the same vertical orientation as the object (up is up, down is down).
- Statement 2 is Incorrect. The image undergoes lateral inversion, meaning the left side of the object appears as the right side of the image, and vice versa. It is not vertically inverted (upside down). Vertical inversion is typically associated with real images formed by converging mirrors or lenses.
- Statement 3 is Incorrect. The image formed by a plane mirror is of the same size as the object. The magnification ($m$) is equal to $+1$. It is neither magnified nor diminished.
Key Takeaway:
Plane mirrors form images that are virtual, erect, laterally inverted, and equal in size to the object. The image distance behind the mirror is exactly equal to the object distance in front of the mirror.