If a convex lens has its object and image distance equal (say x) the focal length is equal to …………………
A) x
B) x/2
C) 2/x
D) 0
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For what position of an obj ect a virtual, erect and diminished image is formed by a concave lens.
D) at any position
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When a lens of focal length f is cut in to two equal halves perpendicular to principal axis, then the focal length of each part of the lens is ………………
Correct option is B) double
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If 40 cm each is the object and image distance respectively for a convex lens then the focal length is ……………………
Correct option is C) 20 cm
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If the image distance of a convex lens of focal length 25 cm is 75 cm then the object distance is ……………………
Correct option is A) -37.5 cm
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An image is formed at distance of 30 cm from the centre of convex lens of focal length 15 cm. The distance of the object is ………………..
Correct option is C) 30 cm
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A convex lens of focal length 20 cm is cut into two halves along principal axis then focal length of each part will be …………………
Correct option is A) 20 cm
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A convex lens of focal length 20 cm is cut into two halves perpendicular to the principal axis then focal length of each part will be ……………….
Correct option is C) 40 cm
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What are convex and concave lenses? For which condition, convex lens will have negative focal length?
1. A lens is said to be convex if it is thicker in the middle and narrowing towards the periphery. According to Cartesian sign convention, its focal length is positive. 2....
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A convex lens has focal length of 2.0 cm. Find its magnifying power if image is formed at DDV.
Given: f = 2 cm, v = D = 25 cm To find: Magnifying power (M.P.) Formula: M.P = 1 + \(\frac{D}{f}\) Calculation: From formula, M.P = 1 + \(\frac{25}{2}\) M.P. = 1 + 12.5 = 13.5
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A point object O is placed on the principle axis of a convex lens of focal length 10 cm at 12 cm from the lens.
U = -12 f = -10 1/v - 1/u = 1/f 1/v + 1/12 = 1/10 1/v = 1/60 \(-\frac{1}{v^2} \)dv or \(\frac{1}{u^2} \)du du = \(\frac{v^2}{u^2} \)du \( \frac{v}{u} \)= same path △u1 = △u2 = 1mm △u1 = △v2 △v2 = vf - vi x2 = △v2 + 1mm x2...
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