Which of the following statements is true?(a) A convex lens has 4 dioptre power having a focal length 0.25 m(b) A convex lens has –4 dioptre power having a focal length 0.25 m(c) A concave lens has 4 dioptre power having a focal length 0.25 m(d) A concave lens has –4 dioptre power having a focal length 0.25 m
Question
Which of the following statements is true?(a) A convex lens has 4 dioptre power having a focal length 0.25 m(b) A convex lens has –4 dioptre power having a focal length 0.25 m(c) A concave lens has 4 dioptre power having a focal length 0.25 m(d) A concave lens has –4 dioptre power having a focal length 0.25 m
Solution
The correct answer is (a) A convex lens has 4 dioptre power having a focal length 0.25 m.
Here's the step-by-step explanation:
The power (P) of a lens is the reciprocal of its focal length (f), measured in meters. The formula is P = 1/f.
For a convex lens, the power is positive, and for a concave lens, the power is negative.
So, if we substitute the given values into the formula:
For option (a), P = 1/0.25 = 4 dioptres, which is a positive value. This is consistent with the fact that a convex lens has positive power. So, this statement is true.
For option (b), a convex lens cannot have a negative power, so this statement is false.
For option (c), a concave lens cannot have a positive power, so this statement is false.
For option (d), P = 1/0.25 = 4 dioptres. However, the power of a concave lens should be negative, so this statement is false because it gives the power as a positive value.
Similar Questions
Which of the following are correct statements about an optical telescope?(e) Two or more convex lenses are used in this telescope.(f) To enter minimum light objective lens is smaller.(g) After entering light rays first refraction and then reflection occurs.(h) Eye piece is smaller than objective lens.(A) e, h(B) e, f (C) f, h(D) f, g, h14. 0.5 kWh = .................... J(A)(B)(C)(D)Space for rough useRao IIT Academy Website : www.raoiit.com4Rao IIT Academy / Pre-Foundation / Homi Bhabha / Official Exam / 2018 / Std. 9th / QP
4. The type of lens used as a magnifying glass(a)Concave lens(b) Convex lens(c)Concavo-convex lens(d) Convexo-concave lens
A thin convex and concave lenses are kept in contact. The combination act as a convex lens of focal length 80 cm. If focal length of the convex lens is 20 cm, then power of the other lens is
A bi convex lens of focal length 10 cm is cut in two identical parts along a plane perpendicular to the principal axis. The power of each lens after cut is _________ D.
A convex lens A of focal length 20 cm and a concave lens B of focal length 5 cm are kept alongthe same axis with a distance d between them. If a parallel beam of light falling on A leaves B asa parallel beam, then the distance d in cm will be
Upgrade your grade with Knowee
Get personalized homework help. Review tough concepts in more detail, or go deeper into your topic by exploring other relevant questions.