Question

The strength of magnification of oil immersion lens is
A) 20x
B) 500x
C) 1000x
D) 100x

Answer 1

Hint:The meaning of the term magnification of lens is the ratio of the height of the image to the height of the object. Oil immersion lens is used in light microscopy for the detection and visualization of biological samples.

Complete answer:
The light microscopy involves focusing light on a specimen that is fixed on a slide and put on the stage of the microscope. This specimen is magnified by the use of an objective lens whose magnification mostly varies from 10x to 100x and finally viewing the specimen through the eyepiece. Oil immersion technique is a type of light microscopy that increases the resolving power of the microscope to a great extent. Oil immersion is different from normal microscopy since in this case the objective lens and the specimen is immersed in a transparent oil that has a high refractive index. Cedar oil which has a refractive index of 1.516 is most commonly used. This leads to an increase in numerical aperture of the objective lens. The magnification of the oil immersion lens is 100x which is much more than the normal objectives and this helps us further to see minute details in the specimen.

Hence the correct answer is option (D)100x.

Note:Oil immersion lens is of importance because many a times in the absence of oil light reflect from the slide containing the specimen resulting in a distorted image. Oil immersion technique minimises this distortion giving detailed images of the specimen. But the oil should be removed from the lens just after use otherwise it can damage the lens.