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An object placed at 20 cm in front of a concave mirror produces three times magnified real image. What is the focal length of the concave mirror?
Options
(a) 15 cm
(b) 6.6 cm
(c) 10 cm
(d) 7.5 cm
Correct Answer:
15 cm
Explanation:
We know that, linear magnification, m = f / (f -u) —-(i)
Given, object displaced, u = -20 cm
m = -3 (All real images are inverted)
Substituting the above values in equation (i), we get
-3 = f / [f – (-20)]
⇒ -3f – 60 = f 4f = -60
⇒ f = – 60 / 4 = -15 cm
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Subject: Physics
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Important MCQs Based on Medical Entrance Examinations To Improve Your NEET Score
- Charge Q is divided into two parts which are then kept some distance apart. The force
- The mean free path of molecules of a gas,(radius ‘r’) is inversely proportional to
- A galvanometer having resistance of 50 Ω requires a current of 100μA to give full
- A and B are two vectors and θ is the angle between them ,if |A x B|=√3(A.B),the value of θ
- Light of wavelength λ is incident on slit of width d. The resulting diffraction
Topics: Ray Optics (94)
Subject: Physics (2479)
Important MCQs Based on Medical Entrance Examinations To Improve Your NEET Score
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