JEE Main 12 Jan 2019 Evening Question 2
Question: Formation of real image using a biconvex lens is shown below If the whole set up is immersed in water without disturbing the object and the screen positions what will one observe on the screen?
[JEE Main Online Paper Held On 12-Jan-2019 Evening]
Options:
A) Image disappears
B) Magnified image
C) Erect real image
D) No change
Show Answer
Answer:
Correct Answer: A
Solution:
- The focal length of the lens is given as $ \frac{1}{f}=( \frac{{\mu_2}}{{\mu_1}}-1 )( \frac{1}{R _1}-\frac{1}{R _2} ) $
If the setup is immersed in water, the focal length of the lens increases.
Hence the image shifts further away from the lens; while the position of screen has been kept unchanged.
So, the image will not be observed on the screen.
