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An Essay about Microscopes

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The word Microscope it given to the tool used to view object that are too small to be seen with the naked eye.

        During the 1st century AD, glass had been invented and the Romans were looking through the glass. They experimented with different shapes of clear glass and one of their samples was thick in the middle and thin on the edges. They discovered that if you held one of these pieces of glass over an object, the object would look larger. Before microscopes as we know where invented, what was considered as a microscope was just really a Magnifying Lens, early biologist used them to study tiny insects such as Fleas, thus the viewer was called a Flea Lens.image00.jpg

         Two Dutch spectacle makers in the 1590’s (Zaccharias Janssen and his father Hans) experimented with lenses and realised that if several lenses were put into a tube and the object is viewed it appears larger than viewed by any magnifying lens, this was the invention of the Compound Microscope.

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The light Microscopes that modern sciences use today are a lot more powerful, sophisticated and widely available at low cost. The term light refers to the method by which light transmits the image to your eye. Compound deals with the microscope having more than one lens. Microscope is the combination of two words; "micro" meaning small and "scope" meaning view. Simple light microscopes of the past could magnify an object to 266x as in the case of Leeuwenhoek's microscope. Modern compound light microscopes, under optimal conditions, can magnify an object from 1000x to 2000x the specimen’s original diameter.

There are also two types of Electron Microscopes; the Transmission Electron Microscope (TEM) and the Scanning Electron Microscope (SEM). Electron Microscopes were developed due to the limitations of Light Microscopes which are limited by the physics of light In the early 1930's this theoretical limit had been reached and there was a scientific desire to see the fine details of the interior structures of organic.


The Transmission Electron Microscope (TEM)

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. The sample is placed inside the microscope's vacuum column through an air-tight door. After the air is pumped out of the column, an electron gun emits a beam of high energy electrons. This beam travels downward through a series of magnetic lenses designed to focus the electrons to a very fine spot. Near the bottom, a set of scanning coils moves the focused beam back and forth across the specimen, row by row. As the electron beam hits each spot on the sample, secondary electrons are knocked loose from its surface. A detector counts these electrons and sends the signals to an amplifier. The final image is built up from the number of electrons emitted from each spot on the sample. image03.png





Google Definitions

http://www.mos.org/sln/SEM/gallery.html (Worth Looking at)


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This student written piece of work is one of many that can be found in our AS and A Level Microscopes & Lenses section.

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Response to the question

As I don't know what the question set is, it is hard to judge how well the student has answered the question. Ultimately I believe that the student has addressed the background knowledge and the fundamental understanding of the topic ...

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Response to the question

As I don't know what the question set is, it is hard to judge how well the student has answered the question. Ultimately I believe that the student has addressed the background knowledge and the fundamental understanding of the topic well. However, I feel there is a lack of detailed knowledge to the functions of the microscope. Obviously this all depends on the requirements of the board, yet whatever the requirements of the board, going that 'one step further' really differentiates an A (A*) grade piece of work from the lower grades. The presence of a bibliography is commendable as the student has clearly acknowledged their sources which prevents any accusations of plagiarism happening.

Level of analysis

The level of analysis in this piece of work is average. It covers the fundamentals of the topic well but lacks depth of knowledge. This would highlight the student's piece of work and further illustrate their understanding of the topic. Also, depending on what the question is, the piece of work lacks an conclusion to sum up the piece of work and the student's findings. This can be vital, but again, depends on the question set. Yet, the response is clearly and logically set out and the use of diagrams helps illustrate what the student is referring to. It is important to remember to source the diagrams used in the work as well.

Quality of writing

The spelling, grammar and punctuation are fine. The technical terms could be put into a glossary and defined - this would be that 'one step further' as it would further show the student's understanding of the topic. The student follows the normal convention in their layout of the work as it is typical (and sensible) to lay it out with headings and diagrams. This helps the examiner clearly identify the part of the question that the student is addressing.

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Reviewed by crystalclearmagic 22/03/2012

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