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प्रश्न
A 50 cm tall object is at a very large distance from a diverging lens. A virtual, erect and diminished image of the object is formed at a distance of 20 cm in front of the lens. How much is the focal length of the lens?
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उत्तर
Since the object is at infinity, the image will be formed at the focus. The image distance will be equal to the focal length of the lens. Therefore, the focal length of the lens is 20 cm.
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संबंधित प्रश्न
What is a virtual image?
Name the spherical mirror which can produce a virtual and diminished image of an object.
A small object is placed 150 mm away from a diverging lens of focal length 100 mm.
(i) Copy the figure below and draw rays to show how an image is formed by the lens.
Figure
(ii) Calculate the distance of the image from the lens by using the lens formula.
What is a spherical mirror?
Name the two kinds of spherical mirrors and distinguish between them.
The diagram below in Figure, shows a convex mirror. C is its centre of curvature and F is its focus. (i) Draw two rays from A and hence locate the position of image of object OA. Label the image IB. (ii) State three characteristics of the image.
Write the spherical mirror's formula and explain the meaning of each symbol used in it.
An object of length 4 cm is placed in front of a concave mirror at distance 30 cm. The focal length of mirror is 15 cm.
- Where will the image form?
- What will be the length of image?
An object 5 cm high forms a virtual image of 1.25 cm high, when placed in front of a convex mirror at a distance of 24 cm. Calculate:
- the position of the image
- the focal length of the convex mirror.
Select the correct option:
Looking into a mirror one finds her image diminished, the mirror is:
Define the following term in relation to concave mirror.
Radius of curvature
Define linear magnification produced by a mirror?
The boxes in figure (a, b, c) represent mirrors; insert a mirror which will reflect the incident ray as shown in the diagram.
A concave mirror can be used to produce a parallel beam of light. Draw a ray to illustrate this.
Which of the following has curved reflecting surface?
Geometric centre of the spherical mirror is ______.
Name the two types of spherical mirrors.
What is the difference between virtual images of an object formed by a concave mirror and a convex mirror?
