Microscopes

Anton Van Leeuwenhoek found that by placing glass lenses (lenses refract light) at certain distances from each other, he could enlarge objects in his field of vision Invented the 1st microscope (light microscope)

Leeuwenhoek developed what is called a simple microscope since it had only one lens. We mostly use compound microscopes since they have more than one lens.

Important Microscopy Terms Magnification Resolving Power the comparison of the real size of a specimen with that of the one viewed under the microscope a.k.a. resolution refers to the clarity of the specimen viewed under the scope Image of pollen grain with good resolution (left) and poor resolution (right)

Parts of a Compound Light Microscope

Coarse focus adjustment knob Focuses the image under low power Usually the bigger knob Makes larger adjustments

Fine focus adjustment knob Sharpens the image under all powers Usually the smaller knob Fine Adjustment Knob

Arm Supports the body tube and is used to carry the microscope Arm

Body Tube Connects the eyepiece to the nosepiece Usually moves during focusing Body Tube

Eyepiece The lens you look through Usually at 10X magnification

Nosepiece a.k.a. revolving nosepiece holds all the objectives and it revolves Nosepiece

Base Supports the microscope and used for carrying the microscope Base

Stage Used to support the slide Stage

Stage Clips Used to hold the slide in place Stage Clips

Diaphragm Used to regulate the amount of light Diaphragm

Light Source Provides light Light Source

Low Power Objective Has the lowest magnification and is the shortest objective Low power objective

Medium Power Objective increases the magnification Medium Power Objective

High Power Objective Provides the most magnification and is the longest objective. High Power Objective

Calculating magnification Determine the magnification of the eyepiece (ocular lens) and each objective. Multiply the magnification of the eyepiece with the magnification of the objective you are using.

Example Calculate the magnification of a microscope with an eyepiece magnification of 10 and objective magnification is 30. Answer: 10 X 30 = 300

Objectives of Microscope Lab To learn the parts of the microscope. To find specimens using low and high power. To make a wet mount. To view your own human cheek cells under the microscope.

Microscope Care Always carry with 2 hands Only use lens paper for cleaning Do not force knobs Keep objects clear of desk and cords

Microscope Parts Eyepiece Body Tube Revolving Nosepiece Arm Objective Lens Stage Stage Clips Coarse Focus This is the exact version of the microscope used in class. Students will be identifying the parts on the microscopes at their desks as we go along and what their functions are. Diaphragm Fine Focus Light Base

Using the Microscope Place the Slide on the Microscope Use Stage Clips Click Nosepiece to the lowest (shortest) setting Look into the Eyepiece Use the Coarse Focus Give students a slide from the “common things” set, each student will practice focusing and changing objectives.

Using High Power Follow steps to first focus using low power Click the nosepiece to the longest objective Do NOT use the Coarse Focusing Knob Instead use the Fine Focus Knob to bring the slide into view Have students exchange slides so they can look at different things, walk them through using the high power objective to focus slides. Emphasize not using the coarse objective during this process, as it will crack the slides. What can you find on your slide?