3) By using the mirror formula :
1/f = 1/v + 1/u
On substituting the values in the above equation we get
1/f = 1/(-50) + 1/(-50) = -1/25
f = -25 cm
4) Characteristics of a concave mirror.
- When it hits and reflects back from the concave mirror's reflecting surface, light converges at a single point. This is why it is sometimes referred to as a converging mirror.
- The size of the image, however, decreases as the distance between the item and the mirror increases, creating a true and inverted image instead.
- A magnified, upright, and virtual image can be obtained when the concave mirror is positioned very close to the item.
- The concave mirror can produce a little or huge, real or virtual image.
A spherical mirror produces an image of magnification -1 on a screen placed at a distance of 50 cm from the mirror.
A screen set 50 cm away from a spherical mirror receives a magnification -1 image from the mirror. (a) It is a concave mirror (b) The distance of the image from the object is 100 cm. (c) The focal length of the mirror is -25 cm.