Computer Applications
Discuss the position and nature of image formed by a concave mirror when an object is moved from infinity towards the pole of mirror.
Answer
The image formed moves away from the concave mirror when an object is moved from infinity towards the pole of mirror.
The image is diminished when the object is beyond centre of curvature, but it becomes magnified as the object comes within the centre of curvature. The image is of the same size of the object when the object is at the centre of curvature.
For the object situated beyond focus, the image is always real and inverted, whereas for the object situated between the focus and pole the image is upright and virtual.
The table below shows the position, size and nature of the image formed by a concave mirror for different positions of the object.
| No. | Position of the object | Position of the image | Size of the image | Nature of the image |
|---|---|---|---|---|
| 1 | At infinity | At the focus | Diminished to a point | Real and inverted |
| 2 | At very far distance | In focal plane | Highly diminished | Real and inverted |
| 3 | Beyond the centre of curvature | Between the centre of curvature and focus | Diminished | Real and inverted |
| 4 | At the centre of curvature | At the centre of curvature | Same size | Real and inverted |
| 5 | Between the centre of curvature and focus | Beyond the centre of curvature | Magnified | Real and inverted |
| 6 | At focus | At infinity | Highly magnified | Real and inverted |
| 7 | Between the focus and the pole | Behind the mirror | Magnified | Virtual and upright |
Related Questions
Why does a driver use a convex mirror instead of a plane mirror as a rear view mirror? Illustrate your answer with the help of a ray diagram.
Draw a ray diagram to show the formation of image by a concave mirror for an object beyond it's center of curvature. State three characteristics of the image.
Discuss the position and nature of image formed by a convex mirror when an object is moved from infinity towards the pole of mirror.
Draw a ray diagram to show the formation of image of an object kept in front of a convex mirror. State three characteristics of the image.