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प्रश्न
The diagram below shows the parallel rays incident on a convex mirror. C is the centre of the curvature of the mirror. By drawing the paths of the reflected rays, label the focus F and hence find the focal length of the mirror.
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उत्तर
We know when the incident ray is parallel to the principal axis then they appear to diverge from a point F.
Geometrically we can find this value and this comes to 2 cm. Centre of curvature = 4 cm.
Focal length = centre of curvature/2.
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संबंधित प्रश्न
What happens when a ray of light falls normally (or perpendiculary) on the surface of a plane mirror?
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(a) virtual principal focus.
(b) real principal focus.
State the two kinds of spherical mirror and distinguish them with the aid of proper diagrams.
State the direction of incident ray which after reflection from a spherical mirror gets reflected along its own path. Give a reason.
AB and CD, two spherical mirrors, from parts of a hollow spherical ball with its centre at O as shown in the diagram. If arc AB = `1/2` arc CD, what is the ratio of their focal lengths? State which of the two mirrors will always form virtual image of an object placed in front of it and why.
A concave mirror forms a virtual image of size twice that of the object placed at a distance 5 cm from it. Find:
- the focal length of the mirror
- position of image
When an object of height 1 cm is kept at a distance 4 cm from a concave mirror, its erect image of height 1.5 cm is formed at a distance 6 cm behind the mirror. Find the focal length of mirror, by drawing.
A point light source is kept in front of a convex mirror at a distance of 40 cm. The focal length of the mirror is 40 cm. Find the position of image.
What is a mirror formula?
A shopkeeper wanted to fix a mirror which will give a maximum view of his shop. What type of mirror should he use? Give reason.
