The document provides an introduction to the light microscope used in 7th grade science. It explains that a light microscope uses two lenses, the eyepiece and objective lens, to magnify specimens between 40-400 times. It then describes each major part of the microscope and its function, including the stage to hold slides, objective lenses to provide magnification, and light source to illuminate samples.

1. Introduction to the Light Microscope

2. Starting with use of a simple lens in ancient
times, to the first compound microscope
around 1590, and up to the microscopes you
are using in 7th grade life science, the
microscope has allowed scientists to make
discoveries about the “invisible world.”
The microscope has
become one of the most
recognizable symbols of
science.

3. Typical Classroom Microscope

4. What is the purpose of a
microscope?
• To magnify or enlarge the image of tiny
objects.
• The microscopes we will use this year in
science can magnify objects 40 times, 100
times, and 400 times the size of the object.

5. What type of microscope will we
be using in class this year?
• In 7th grade science, we use a compound
light microscope for most of our lab
activities.
• A light microscope uses light as a source
of energy for viewing objects.
• A compound microscope contains two
lenses for magnifying a specimen at the
same time, the eyepiece (ocular) and one of
the objective lenses.

6. Eyepiece

7. Eyepiece
• Also known as the ocular
• Contains the first lens you look through -
usually a magnification of 10x
• Located on the top of the body tube

8. Objective Lenses

9. Objective Lenses
• Used in combination with the eyepiece to
provide a range of magnification
• Magnification ranges from 40x to 400x
• Located on the nosepiece at the bottom of
the body tube

10. Nosepiece

11. Nosepiece
• Holds the objective lenses
• Rotates to enable magnification
• Located at the bottom of the body tube

12. Arm

13. Arm
• Supports the upper parts of the microscope
• Used to carry the microscope
• When carrying a microscope, always have
one hand on the arm and one hand on the
base. Use two hands!!

14. Base

15. Base
• Supports the whole microscope
• Used to carry the microscope
• When carrying a microscope, always have
one hand on the arm and one hand on the
base. Use two hands!!

16. Stage

17. Stage
• Supports the slide
• The slide contains the specimen or object
that you are viewing with the microscope.

18. Stage Clip

19. Stage Clip
• Helps to hold the slide in place
• Usually one on each side of the hole (stage
opening) = 2 stage clips
• The stage opening allows light to pass from
the light source to the lenses.

20. Light Source

21. Light Source
• Provides light necessary for viewing the
specimen
• Usually either a mirror or illuminator
• Sends light through the stage opening to
the diaphragm

22. Diaphragm

23. Diaphragm
• Wheel or lever located below the stage
opening
• Regulates the amount of light that can enter
the lenses
• May need to be adjusted based on the
thickness of the specimen being studied

24. Coarse Adjustment
Knob

25. Coarse Adjustment Knob
• Raises and lowers the stage or objective
lenses
• Used only when focusing the low power
(4x) objective lens

26. Fine Adjustment Knob

27. Fine Adjustment Knob
• Raises and lowers the stage or objective
lenses a small distance for exact focusing
• Used when focusing the medium power
(10x) and high power (40x) objective
lenses

28. Let’s Review...
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