นอกจากการดูบทความนี้แล้ว คุณยังสามารถดูข้อมูลที่เป็นประโยชน์อื่นๆ อีกมากมายที่เราให้ไว้ที่นี่: ดูเพิ่มเติม
คลิปวิดีโอนี้สร้างขึ้นเพื่อจัดการเรียนรู้ให้แก่นักเรียนชั้นมัธยมศึกษาชั้นปีที่ 1 รายวิชาวิทยาศาสตร์พื้นฐาน 1
How to Correctly Use a Microscope
In order to teach 7th graders how to act while in the science lab, this 7th grade teacher made her own intructional videos on how to use equipment and act in class. Check out the RIGHT and WRONG ways to act
บทที่ 3 กล้องจุลทรรศน์และการวัดขนาดเซลล์ EP 2
WHAT ARE LIGHT AND ELECTRON MICROSCOPES? – HOW DO THEY WORK?
Light and electron microscopes
The beauty of biology and all that we know today is due to the invention of microscopes. The light microscope uses light as a source of radiation and has shown us inside cells. It shows us simple structures like the nucleus, the cell wall and the cell membrane. Light microscope is still used in basic studies in schools today.
Microscopes had been available since the beginning of the 17th century but a lot of improvements made in the quality of glass lenses in the early 19 century. The branch of biology dealing with microscope design, slide preparation and examination is called cytology. The general structure of animal and plant cell is also due to the light microscope.
Then came the electron microscopes, which made our microscopic world more detailed. Due to the electron microscopes we not only saw the cell wall, the nucleus and the cytoplasm but we also saw the more minute organelles like the mitochondria, endoplasmic reticulum and the Golgi apparatus.
The light microscopes were doing great, but no matter how much their designs improved, there was extent to which the light microscopes could show. Anything smaller than 200 nm could not be seen. In an electromagnetic spectrum, there are radiations smaller than light, these are ultraviolet radiations and xrays.
Microscopes with both ultraviolet and xray radiation were built, but alas, xrays could not be focused and so these designs were discarded.
Electrons are negatively charged particles which orbit the nucleus of an atom. When a metal becomes very hot some of its electrons gains so much energy that they escape from their orbits, like shooting stars.
Free electrons behave like electromagnetic radiation they have a very short wavelength the greater the energy the shorter the wavelength. Electrons are very suitable form of radiation for microscope for two major reasons. Firstly wavelength is extremely short and secondly because they are negatively charged they can be focused easily using electromagnets. The magnet can be made to alter the path of the being the equivalent of a glass lens bending light.
There are two types of electron microscopes in use today. In the transmission electron microscope, the beam of electrons is passed through the specimen before being viewed. Only those electrons that are transmitted are seen. This allows us to see thin sections of specimens and thus to see inside cells.
In scanning electron microscope, the electron beam is used to scan the surfaces of structures and only the reflected beam is observed. The advantage of this is that surface structure, for example,like the chitinous outer body of insects can be seen in great detail.
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🔬 148 – Comparing a TOY Microscope with a \”REAL\” Microscope | Amateur Microscopy
How good are toy microscopes? Comparing different microscopes to each other. I collect a pond water sample and put it under three different microscopes.
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