Question

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

Answer 1

Answer: (B)

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 $50\,\mathring{A}$ and its magnification power is usually around $20,000$ times.