JEE Main 2018PhysicsRay OpticsHardMCQ

JEE Main 2018 — Ray Optics Question with Solution

JEE Main 2018 (15 Apr)

Question

A particle is oscillating on the x-axis with an amplitude 2 cm about the point x0=10 cm with a frequency. A concave mirror of focal length 5 cm is placed at the origin (see figure).


Identify the correct statements?
(i) The image executes periodic motion.
(ii) The image executes non-periodic motion.
(iii) The turning points of the image are asymmetric with respect to the image of the point at X=10 cm.
(iv) The distance between the turning points of the oscillation of the image is 10021 cm.

Choose an option

Show full solutionCorrect option: B
Correct answer
B(i, iii, iv)

Step-by-step explanation

Recall the proper formula of mirror formula, 1f=1v+1u, given f=-10 cm and u=-5 cm then the formula of the concave mirror, -110=1v-15⇒v=-10 cm. As, image copies the time period of the object A is right as well. It will be a periodic motion. For one extreme, 

⇒-18+1v=1-5⇒v=-403 cm, right arrow.

For other extreme, 

⇒-112+1v=1-5⇒v=-760 cm. These points are asymmetrical about x0=10 cm. Now amplitude of oscillation of image, ⇒403-607=10021 cm.

 

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About this question

This is a previous-year question from JEE Main 2018, covering the Ray Optics chapter of Physics. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.