Special characteristic of electron microscope-

Ans. is 'b' i.e., Tungston filament is used Electron Microscope vs Light MicroscopeElectron MicroscopeLight MicroscopeIlluminating source is beam of electronsIlluminating source is lightIt is very large and complicatedMicroscope is compact and handyOnly fixed specimens are studiedBoth living and fixed specimens can be studiedThe objects is ultrathin, 0-1 mm or belowThe object is 5 mm or thickerOnly dehydrated specimens are usedThe specimen need not be dehydratedVacuum is essential for its operationA vacuum is not requiredHigh voltage electric current is required (50,000 volts and above)There is no need for high voltage electricityTungsten filament is used to produce electronsA filament is not usedIt has a cooling system to take out heat generated by high voltage electric currentThere is no cooling systemThere is risk of radiation leakageRadiation risk is absentIt employs elecromagnetsLight microscope uses glass lensesImage is seen only on a fluorescent screenImage can be seen directlySpecimen is coated with heavy metals in order to reflect electronsSpecimen is stained by coloured dyesImage black and whiteImage is coloredResolving power is 0-5-5-0 Adeg, though theoretically it can be 0-25 AdegResolving power is 0-25 mm or 250 nm (2500Adeg)Magnification is up to 300,000Magnification is upto 4000Electron microscope is used in the study of external surface (Scanning Electron Microscope SEM), ultra structure of cell and very small organism (Transmission Electron Microscope TEM)It is used for the study of detailed gross internal structure