MICROSCOPY I

Question 1

LIGHT MICROSCOPES

Answer 1

→ light microscopes: use visible light to see specimens, widely used in biological sciences
Simple light microscope: uses one lens and cannot reach high magnifications
Compound light microscope: uses 2 lenses, objective lens and eyepiece to produce images.

Question 2

ELECTRON MICROSCOPES

Answer 2

→ electron microscopes: use accelerated electrons (which have very short wavelengths) as a source of illuminating radiation.
TEM (transmission electron microscope): is used to see very thin specimens. Uses an electron beam to scan across the specimen. Remitted electrons are measured to form the image.
SEM (scanning electron microscope): depends on emission from secondary electrons and surface of specimen. Contrast image depends on which electrons did and didn’t pass through the sample
Electron microscopes have a higher resolving power and can thus reveal smaller objects, electrons also emit wavelengths (as they have both wave and particle characteristics) up to 100,000 times shorter than a photon! They also use vacuums.

Question 3

MAGNIFICATION

Answer 3

Is basically how much bigger the specimen looks under the microscope.
→ total magnification: is the product of lens magnification

Question 4

RESOLVING POWER

Answer 4

→ is the ability to clearly differentiate 2 different objects under the microscope
→ high resolution
- this depends on light wavelength (the shorter the better), and refractive index (immersion oil is used to keep to constant)
→ ability to differentiate between background and object
- Utilized with contrast and staining