Direction for: In each of the following questions a statement of Assertion is given followed by a corresponding statement of Reason just below it. Of the statements mark the correct answer as
Assertion: Transmission Electron Microscope (TEMJ provides two dimensional images. Reason: Scanning Electron Microscope (SEM) provides three dimensional images.A) If both Assertion and Reason are true and the Reason is the correct explanation of the Assertion
B) If both Assertion and Reason are true but the Reason is not the correct explanation of the Assertion
C) If Assertion is true but Reason is false
D) If both Assertion and Reason are false
Correct Answer: B
Solution :
Electron microscope have very high resolving power. It uses a beam of electrons for illumination of object and image formation and electromagnetic lenses (ie, condenser, objective and projector). There are two types of electron microscope: (i) Transmission Electron Microscope (TEM): It is used to study internal structure of the specimen and gives two dimensional (2D) view. TEM is the most commonly used electron microscope, resolution power is 1-2 lac times. (ii) Scanning Electron Microscope (SEM): SEM if especially useful for examining the surface of a specimen. It gives three dimensional (3D) surface view of objects. The resolution power of a SEM is about \[50\overset{\text{o}}{\mathop{\text{A}}}\,\] and its magnification power is usually around 20, 000 times.
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