Find the focal length and power of a convex lens, which when placed in contact with a concave lens of focal length `25 cm` forms a real image `5` times the size of the object placed `20 cm` from the combination.
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An eye-piece consists of a concave lens of focal length 2f and a convex lens of focal length 3f separted by a distance `(f)/(2)`. They are of the same
Correct Answer - Free from chromatic aberration but not spherical, yes
2 Answers 1 views
Calculate the focal length of a convex lens of crown glass of dispersive power 0.012 and concave lens of dispersive power 0.020 that from an achromati
Correct Answer - `r_("common")=1.11 m,0.644m`
2 Answers 2 views
An object is placed 20 cm to the left of a convex lens of focal length 10 cm. If a concave mirror of focal length 5cm is placed 30 cm to the right of
Correct Answer - The image coincides with the object
2 Answers 1 views
A concave lens of focal length 20 cm is placed 15 cm in front of a concave mirror of radius of curvature 26 cm and further 10 cm away from the lens is
Correct Answer - 140 cm in front of the lens
2 Answers 9 views
A convex lens of focal length `15 cm` is placed in front of a convex mirror. Both are coaxial and the lens is `5 cm` from the apex of the mirror. When
Correct Answer - 55 cm
2 Answers 1 views
A concave mirror forms a real image four times as tall as the object placed 10 cm infront of mirror. Find the position of the image and the radius of
Correct Answer - 40 cm in front of the mirror, `R =- 16 cm`
2 Answers 1 views
The focal length of a concave-convex lens of radii of curvature 5 cm and 10 cm is 20 cm. what will be its focal length in water ? Given `.^(a)mu_(w) =
Correct Answer - `-80 cm`
2 Answers 2 views
A source of light and a screen are placed 90 cm apart. Where should a convex lens of 20 cm focal length be placed in order to form a real image of the
Correct Answer - 60 cm or 30 cm from the source
2 Answers 2 views
A concave lens focal length 10 cm is placed on the axis of concave mirror of 10 cm radius at a distance of 5 cm from the mirror. An object is placed s
Correct Answer - 10 cm from the lens
2 Answers 1 views
A compound lens has been formed by joinined a convex and a concave lens, each of focal length 30 cm. what is the focal length of the combination? What
Correct Answer - Infinite, zero
2 Answers 1 views