What major advantage does phase-contrast microscopy haveover staining?

What is the highest magnification of the following microscopes?Bright fieldDark fieldPhase-contrastFluorescenceConfocalScanning EMTransmission EMScanned-Probe

In light microscopy, when magnification is increased, the lens focuses closer to the sample.  This makes the user more likely to ram the sample into the lens.  Why is it common for the lens to focus closer to the sample at higher magnifications? What can be done to mitigate this risk?

The diffraction limit is an unbeatable barrier limiting the effective resolution of light microscopy due to the inherent wavelength of light.True or False

Why don't you heatfix a negative stain slide?

Compare and contrast the operation of Optical microscopy and TEM in terms of Abberations

1.Why is wavelenth the main limiting factor on limit of resoltuin in light microscopy? 2.Assuming that all other variables remain constant, explain why light of shorter wavelengths will produce a clearer image that light of longer wavelenths. 3. Why aren't the magnification of both ocular lenses of a binocular microscope used to calculate total magnification?

Define dyes and describe the basic chemistry behind the processof staining.

Why do you use immersion oil with 100X objective lens?

Adjusting the objective aperture is an important step to obtain phase contrast in TEM. Compare the differences in objective aperture operation between diffraction contrast and phase contrast.