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प्रश्न
The distance from the pole to the focus is called ______.
विकल्प
pole length
focal length
principal axis
None of the above
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उत्तर
The distance from the pole to the focus is called focal length.
Explanation:
The distance from the pole (the center of a spherical mirror or lens) to the focus (the point where light rays converge or appear to diverge) is called the focal length.
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संबंधित प्रश्न
A student focused the Sun rays using an optical device 'X' on a screen S as shown.
From this it may be concluded that the device 'X' is a (select the correct option)
(A) Convex lens of focal length 10 cm.
(B) Convex lens of radius of curvature 20 cm.
(C) Convex lens of focal length 20 cm.
(D) Concave mirror of focal length 20 cm.
Explain the following term related to spherical lenses:- centres of curvature
Explain the following term related to spherical lenses: focal length
Name the two types of spherical mirrors. What type of mirror is represented by the:
back side of a shining steel spoon?
What is the relation between the focal length and radius of curvature of a spherical mirror (concave mirror of convex mirror)? Calculate the focal length of a spherical mirror whose radius of curvature is 25 cm.
What is a spherical mirror?
State the number of images of an object placed between two mirrors, formed in each case when mirrors are inclined to each other at (a) 90°, and (b) 60°.
An object forms a virtual image which is 1/8th of the size of the object. If the object is placed at a distance of 40 cm from the convex mirror, calculate:
- the position of the image
- the focal length of the convex mirror.
Complete the following diagrams shown in the following figures by drawing the reflected rays.
Assertion: Incident ray is directed towards the centre of curvature of spherical mirror. After reflection it retraces its path.
Reason: Angle of incidence (i) = Angle of reflection (r) = 0°
