Comparing the Light and Electron Microscope

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Comparing the Light and Electron Microscope

In this essay I am going to be comparing the light and electron

microscope, I will look at the advantages and disadvantages of each

microscope and then analyse my findings to see if one is better than

the other.

The light, or optical microscope as it is also known was invented in

the 17th century, it has been refined in many ways over the years but

it is essentially still the same. The light microscope works by; light

rays from a light source beneath the stage are through to glass lenses

in series. The two lenses are called the objective lens and the ocular

(eyepiece) lens. Depending on their strength these two lenses on their

own routinely provide magnifications of up to 400 times. There is a

limit to the amount of detail the light microscope can show, this

limit is set by the resolving power. The resolving power is the

minimum distance by which two points must be separated in order for

them to be perceived as two separate points, rather than a single

fused image. For the light microscope this distance is approximately

0.2µm. So in theory it might seem possible to magnify an object

indefinitely by means of glass lenses in series. This has been put

into practice and has only produced a larger and fuzzier picture; so

the resolution is not improved and no more detail is visible. The

resolution of the light microscope is imposed by the wavelength of

visible light, and means that little is gained by magnifying an object

more than 1500 times. This limits the amount of structural detail that

can be seen within a cell. Higher magnification with good resolution

can be obtained by using a spec...

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...Disadvantages

Cheap to purchase and operate

Expensive to purchase and operate

Small and portable- can be used almost anywhere

Very large and must be operated in special rooms

Unaffected by magnetic fields

Affected by magnetic fields

Preparation of material is relatively quick and simple, requiring only

a little expertise

Preparation of material is lengthy and requires considerable expertise

and sometimes complex equipment

Material rarely distorted by preparation

Preparation of material may distort it

Natural colour of the material can be observed

All images are black and white

Disadvantages

Advantages

Magnifies objects up to 2000x

Magnifies objects over 500,000x

The depth of the field is restricted

It is possible to investigate a greater depth of field

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