JEE MAIN - Physics (2021 - 26th February Evening Shift - No. 13)
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 :
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 :
A is true but R is false
A is false but R is true
Both A and R are true and R is the correct explanation of A
Both A and R are true but R is NOT the correct explanation of A
Explanation
The formation of image with simple microscope is shown below.
_26th_February_Evening_Shift_en_13_1.png)
_26th_February_Evening_Shift_en_13_2.png)
Here, $$\theta ' = {h \over {{u_0}}} = {{h'} \over D} = {{h'} \over {25}}$$
where, D = 25 cm (least distance of distinct vision)
Here, $$\theta$$' is same for both object and image, hence Assertion is true.
Magnification, $$m = {{\theta '} \over \theta } = {D \over {{u_0}}}$$
Hence, if u0 < D (25 cm), hence, the value of $$\theta$$' will obtain large.
So, option (c) is the correct.
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