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प्रश्न
When a spherical mirror is held towards the sun and its sharp image is formed on a piece of a carbon paper for some time, a hole is burnt in the carbon paper.
At which point of the spherical mirror the carbon paper is placed?
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उत्तर
The carbon paper was kept at the focus of the spherical mirror.
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संबंधित प्रश्न
A 4 cm tall object is placed on the principal axis of a convex lens. The distance of the object from the optical centre of the lens is 12 cm and its sharp image is formed at a distance of 24 cm from it on a screen on the other side of the lens. If the object is now moved a little away from the lens, in which way (towards the lens or away from the lens) will he have to move the screen to get a sharp image of the object on it again? How will the magnification of the image be affected?
Explain the following term related to spherical lenses:- principal focus
A concave mirror always forms a real image.
A ray of light is incident normally on a plane mirror. What will be the
angle of incidence?
What type of image is formed:
on a cinema screen?
What kind of mirror is required for obtaining a virtual image of the same size as the object?
Define the following terms in the context of spherical mirrors :
(i) Pole
(ii) Centre of curvature
(iii) Radius of curvature
(iv) Principal axis
Mention the types of mirrors used as (i) rear view mirrors, (ii) shaving mirrors. List two reasons to justify your answers in each case.
Draw a ray diagram to show the formation of image by a concave mirror for the object beyond its centre of curvature. State three characteristics of the image.
What is meant by magnification? Write its expression. What is its sign for the (a) real (b) virtual, image?
(a) When a concave mirror is used as a shaving mirror, where is the person's face in relation to the focus of mirror?
(b) State three characteristics of the image seen in part (a).
An object 5 cm high is placed at a distance 60 cm in front of a concave mirror of focal length 10 cm. Find the position and size of the 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.
Find the height of the image of a body of height 1.5m in a mirror with a magnification of 1.5.
Numerical problem.
The radius of curvature of a spherical mirror is 25 cm. Find its focal length.
A ray of light is incident towards a plane mirror at an angle of 30° with the mirror surface. What will be the angle of reflection?
