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Microscopes - 7th Grade

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by

William Begoyan

on 18 September 2017

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Transcript of Microscopes - 7th Grade

By: Mr. Begoyan

Page 13 in ISN
(page 68-70 in textbook)


AVID EQ: How do microscopes work and what are their limitations?
Microscopes
Early Microscopes
A

microscope

is an optical tool that makes smaller images appear larger.
1590
– first primitive microscope.
1655
– Robert Hooke used a simple microscope to observe pores in cork.
He called them “cells”
In the
1670's

Antonie van Leeuwenhoek
discovered microscopic life in a drop of pond water using a primitive microscope.
Magnification vs Resolution

Magnification:
increase of an object’s apparent size .
Resolution:
power to show details clearly.
Both
are needed to see a clear image.


Light
Microscope

1. When was the first microscope made?

2. What did Antonie van Leeuwenhoek discover?

3. Describe Magnification & Resolution. Why do you need both?
Questions
First made in 1931
Used to observe VERY small objects: viruses, DNA, parts of cells.
Uses beams of electrons rather than light.
Much more powerful than light microscopes.
Specimen
must be dead.
2 types.

Electron
Microscopes

Scanning Electron Microscope
(SEM)
.
Can magnify up to 100,000.
3D image.

Transmission Electron Microscope
(TEM).
Can magnify up to 250,000 times.
2D image only.

4. How do electron microscopes work?

5. Can the specimen be alive for electron microscopes to use?

6. Which electron microscope has greater magnification? Which can produce a 3D image?

Original microscope, most widely used.
Uses light, light passes through 2 or more lenses.
Can magnify up to 2000 times, limited by light.
Total magnification = ocular lens x objective lens.

1. Eyepiece + Ocular lens
(lens #1)
2. Arm -
only hold a microscope by it's arm!
3. Coarse Focus -
use first
5. Base
6. Power Switch
(find it on yours)
7. Illuminator -
light source
4. Fine Focus -
use second
8. Diaphragm -
adjust the amount of light that gets through.
9. Stage -
slide goes here
10. Stage clips -
securely holds slide
12. Rotating head
11. Objective lenses -
4x, 10x, 100x
Homework
Part 1: On page 12, compare and contrast light and electron microscopes.
Part 2: Compare and contrast TEM and SEMs.
Full transcript