Q. The magnifying power of an astronomical telescope can be decreased by
✅ Correct Answer: (C)
increasing the focal length of the eyepiece
Explanation: The magnifying power (M) of an astronomical telescope is given by the formula:
M = F0 / Fe
where:
= Focal length of the objective lens
= Focal length of the eyepiece
To decrease magnification, we need to increase (the focal length of the eyepiece), as it is in the denominator of the formula.
Other Options Explained:
(A) Decreasing the focal length of the eyepiece → Increases magnification.
(B) Increasing the focal length of the objective → Increases magnification.
(D) None of these → Incorrect, as option (C) is correct.
Thus, the correct answer is (C) Increasing the focal length of the eyepiece.
Explanation by: Mr. Dubey
The magnifying power (M) of an astronomical telescope is given by the formula:
M = F0 / Fe
where:
= Focal length of the objective lens
= Focal length of the eyepiece
To decrease magnification, we need to increase (the focal length of the eyepiece), as it is in the denominator of the formula.
Other Options Explained:
(A) Decreasing the focal length of the eyepiece → Increases magnification.
(B) Increasing the focal length of the objective → Increases magnification.
(D) None of these → Incorrect, as option (C) is correct.
Thus, the correct answer is (C) Increasing the focal length of the eyepiece.
M = F0 / Fe
where:
= Focal length of the objective lens
= Focal length of the eyepiece
To decrease magnification, we need to increase (the focal length of the eyepiece), as it is in the denominator of the formula.
Other Options Explained:
(A) Decreasing the focal length of the eyepiece → Increases magnification.
(B) Increasing the focal length of the objective → Increases magnification.
(D) None of these → Incorrect, as option (C) is correct.
Thus, the correct answer is (C) Increasing the focal length of the eyepiece.