Question

Read the following paragraph and answer any 4 questions from Q 7 (i) to (v) (4×1 = 4 marks)
Lenses are precisely shaped pieces of glass that have been developed and used in corrective glasses, telescopes, microscopes, binoculars, and magnifying glasses. Refraction of the rays of light reflected from causes the rays to form a visual image of the object. This image may be either real or visible on a screen—or virtual-visible only upon looking into the lens, as in a microscope. The image may be much larger or smaller than the object, depending on the focal length of the lens and on the
distance between the lens and the object. If a lens has a shorter focal length it is said to be more powerful.
7.(i) You have two lens A and B of focal length +50cm and -50cm respectively. The nature and power of the lenses respectively is
a. Concave, -2 D ; Convex, +2 D
b. Convex, +2 D; Concave, - 2
c. Concave, +2 D Convex, - 2 D
d. Convex, - 2 D ; Concave, + 2 D
7.(ii) Power of a lens is -4D. What would be the nature formed by this lens?
a. Real, inverted, enlarged
b. Real, upright, diminished
c. Virtual, inverted, enlarged
d. Virtual, erect, diminished
7.(iii) If the powers of two lenses L 1 and L 2 are in the ratio of 3:2, What would be the ratio of the focal lengths of L 1 and L 2?
a. 3:2
b. 2:3
c. 9:4
d. 4:9
7.(iv) A 5 cm tall object was placed perpendicular to the principal axis, at a distance of 20 cm in front of a convex lens of focal length 25cm. The image position and image height would be?
a. 100 cm behind the lens; 1 cm high
b. 100 cm in front of the lens, 1 cm high
c. 100 cm behind the lens, 25 cm high
d. 100 cm in front of the lens, 25 cm high
7.(v) A convex lens and a concave lens, each having same focal length of 25 cm, are put in contact to form a combination of lenses. The power in diopters, of the combination is:
a. 25
b. 50
c. Infinite
d. Zero

Answer 1

the answer is zero

hope it is helpful