Question

Consider the following statements regarding a simple microscope:
(P) It allows us to keep the object within the least distance of distant vision.
(Q) Image appears to be biggest if the object is at the focus.
(R) It is simply a convex lens.
A. Only (P) is correct.
B. Only (P) and (Q) are correct.
C. Only (Q) and (R) are correct.
D. Only (P) and (R) are correct.

Answer 1

Hint A microscope is an optical device which is used to magnify and view small objects in more detail. Normally microscopes and telescopes consist of two lenses, objective and eyepiece but a simple microscope uses only a single lens.

Complete step by step answer:
A microscope is used to enlarge the image of a small object which is kept in front of it. It magnifies the object using angular magnification, which means that the visible angle covered by the image of the object will be more than that of the original object. A simple microscope consists of a biconvex lens.
Verifying the statements given in the question:
Statement P: The objects viewed through a microscope are kept between the focus and the optical center of the lens. This results in formation of an erect and enlarged image of the object, which lies at the least distance of distant vision. Thus it is the image which is formed within the least distance of distant vision and not the object. Therefore the statement is wrong.
Statement Q: A simple microscope uses a single convex lens for the magnification and the object is placed between the optical center and pole. As we look into the properties of the image formed by a convex lens, it is found that- when the object lies between the optical center and the focus, it gets larger in size as it is moved towards the focus of the lens. At focus, a very large, real and inverted image is formed, after which all the images are real and enlarged but smaller in comparison to the image formed at the focus. Therefore it is true that image appears to be biggest if the object is at the focus.
Statement R: A simple microscope has a single biconvex lens. It is a converging lens and can form highly enlarged images when the object is placed at a distance within its focus. Therefore, this statement is also true.
Statements Q and R are true.

Option (C) is correct.

Note It is important to place the object between the optical center and focus of the convex lens, because after that if the distance of the object is further increased, the image becomes real which makes it inverted. And with increasing distance it only gets smaller.