| ⇦ | 
| ⇨ |
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
Related Questions: - A proton beam enters a magnetic field of 10⁻⁴ Wb/m² normally. If the specific charge
- A thin circular ring of mass M and radius R is rotating in a horizontal plane about
- The half life of radium is about 1600 year. Of 100 gram of radium existing now
- Changing magnetic fields can set up current loops in nearby metal bodies
- The potential energy of a system increases if work is done
Topics: Ray Optics
(94)
Subject: Physics
(2479)
Important MCQs Based on Medical Entrance Examinations To Improve Your NEET Score
- A proton beam enters a magnetic field of 10⁻⁴ Wb/m² normally. If the specific charge
- A thin circular ring of mass M and radius R is rotating in a horizontal plane about
- The half life of radium is about 1600 year. Of 100 gram of radium existing now
- Changing magnetic fields can set up current loops in nearby metal bodies
- The potential energy of a system increases if work is done
Topics: Ray Optics (94)
Subject: Physics (2479)
Important MCQs Based on Medical Entrance Examinations To Improve Your NEET Score
18000+ students are using NEETLab to improve their score. What about you?
Solve Previous Year MCQs, Mock Tests, Topicwise Practice Tests, Identify Weak Topics, Formula Flash cards and much more is available in NEETLab Android App to improve your NEET score.
Share this page with your friends
Leave a Reply