Question 139: Ray Optics

Question

Given below are two statements : one is labeled as Assertion A and the other is labeled as Reason R.
Assertion A : For a simple microscope, the angular size of the object equals the angular size of the image.
Reason R : Magnification is achieved as the small object can be kept much closer to the eye than 25 cm and hence it subtends a large angle.
In the light of the above statements, choose the most appropriate answer from the options given below :

Accepted Answer

The formation of image with simple microscope is shown below.
Here, $$	heta ' = {h \over {{u_0}}} = {{h'} \over D} = {{h'} \over {25}}$$
where, D = 25 cm (least distance of distinct vision)
Here, $$	heta$$' is same for both object and image, hence Assertion is true.
Magnification, $$m = {{	heta '} \over 	heta } = {D \over {{u_0}}}$$
Hence, if u
0
< D (25 cm), hence, the value of $$	heta$$' will obtain large.
So, option (c) is the correct.

Answer

A is true but R is false

Answer

A is false but R is true

Answer

Both A and R are true and R is the correct explanation of A

Answer

Both A and R are true but R is NOT the correct explanation of A

Ray Optics

Choose the correct answer: