Microscopes and Magnification

Magnification & Resolution
Magnification = Image Size / Actual Size. (How much bigger the image is compared to the specimen.
Resolution = The point at which a microscope can distinguish between two points that are close together.
Increasing the magnification, will not make the image clearer.

Light Microscopes

• It uses light (duh)
• Maximum resolution: 0.2 micrometres.
• Usually used to look at whole cells or tissues
• Maximum magnification: 1500X

Transmission Electron Microscopes

• Uses electrons instead of light.
• Produces more detailed images
• Uses electromagnets to focus a beam of electrons which are transmitted through the specimen.
• Denser parts of the specimen absorb more electrons, so they appear darker on the image produced.
• they are often used to look at organelles.
• they can only be used on thin specimens.

Scanning Electron Microscopes

• Scans a beam of electrons across the specimen.
•  This knocks electrons off the specimen, which are collected in a cathode ray tube to form an image. 
• The image produced shows the surface of the specimen and can be a 3D image. 
• However, they give a lower resolution that TEMs.

	Light Microscope	TEM	SEM
Maximum Resolution	0.2µm	0.0002 µm	0.002 µm
Maximum Magnification	X1,500	X1,000,000 +	X500,000