2018 · Q2
Which of the following statements about optical microscope is/are correct?
- 1Both the eyepiece and objective of a microscope are convex lenses.
- 2The magnification of a microscope increases with increase in focal length of the objective.
- 3The magnification of a microscope depends upon the length of the microscope tube.
- 4The eyepiece of a microscope is a concave lens.
Select the correct answer using the code given below.
general-sciencephysics-light-electricity
- A1 and 3
- B3 only
- C3 and 4
- D1, 2 and 4
Explanation
A compound microscope uses two convex (converging) lenses — the objective near the specimen and the eyepiece near the eye — so statement 1 is true and statement 4 (concave eyepiece) is false. Total magnification is the product of the two lens powers, and the objective's contribution grows with the tube (image) length, so statement 3 is true. A shorter objective focal length gives higher magnification, so statement 2 is false. Therefore only statements 1 and 3 are correct.