Microscope

Head

Supports an attachment for the ocular lenses

True or False: NEVER USE THE COARSE FOCUS KNOB WITH THE HIGH POWER LENS

TRUE: The coarse adjustment knob is used for large adjustments when focusing a microscope. By the time you've gotten up to the high power objective lenses, the lens is quite close to the stage and using the coarse adjustment knob could cause you to crack the slide or lens. You should only use the coarse adjustment knob on the lowest objective of the microscope. After that, you should only need to use the fine adjustment knob.

Voltage Control Dial

The light intensity is controlled by a voltage control dial on the side of the microscope.

Total Magnification

Total magnification of a microscope is the product of the magnifications of the ocular lens and the objective lens being used.

What is meant when it is said that the resolving power of the unaided eye is 0.1 mm?

To your unaided eye, they would look like one thick line rather than two separate lines.

What is meant when it is said that the resolving power of the unaided eye is 0.1mm?

You can't see it unless you use a microscope. To your unaided eye, they would look like one thick line rather than two separate lines. If they were a little farther apart than 0.1mm you could probably resolve them into two separate lines.

Draw the letter P as it would appear when viewing under the microscope.

d

Why is it important to center the specimen to be viewed before switching to a higher power?

field of view becomes smaller and if the field of view is not focused/moved when you change to high power you would not see the field of view

When you move the slide to the right, the image moves to the . . .

left (opposite direction)

Difference between Magnification and Resolving power

magnification refers to the enlargement of the object being studied, while resolving power pertains to the capacity of an optical medium, such as a lens, to distinguish between proximate objects as distinct images.

Revolving nose piece

rotates the desired objective lens into viewing position

Arm

supports the head and connects it to the base.

Base

supports the microscope and houses the illumination.

Stage

Flat surface where the microscope slide is placed.

Mechanical stage control: Moving the slide closer to you. Which way does the e appear to move?

Further downward

Which way does the "e" appear to move?

Further downward

Ocular Lens (eyepiece) (10x)

Further magnifies the image produced within the microscope by the objective lens.

Condenser

Concentrates the light from the light source. The condenser should be raised into it's highest position.

Which objective lens has the greatest diameter of field?

High Power Objective Lens (40x)

Mechanical Stage

Holds the slide in place. The Mechanical stage controls provide precise movement of the slide.

Explain how you would measure a specimen under a microscope with a known diameter field?

If you know the Diameter of field, you can estimate the size of the objects seen under the microscope by comparing them to the known diameter of field.

Magnification

Is the ability of the lens to enlarge the visual image of the object.

Define Resolving power

Is the ability of the microscope to distinguish fine detail.

Resolving Power

Is the ability of the microscope to distinguish fine detail.

Explain why the coarse focus knob should never be used when the high power objective is in the viewing position.

It can break the slide or crush the specimen being used and break the lens.

Why is it necessary when using the microscope to always start with the scanning lens?

It magnifies the object

What difference did you notice of the letter "e"?

It's upside down

4. General type of microscope: Scanning Electron Microscope

Scanning Electron Microscope = SEM It is a reflected electron beam

Which objective lens should be in place when the microscope is put away?

Scanning Objective Lens

Which objective lens has the least diameter of field?

Scanning Objective Lens (4x)

Which objective lens should you always start with?

Scanning lens

Square A is approximately ______ times larger than square B

3x

What is the total magnification of a microscope with a 10x ocular and high power (40x) objective in the viewing position?

400x

Calculate the High power objective lens 40x multiply by the Ocular Lens 10x

40x multiplied by 10x = 400x

Calculate the Scanning lens of 4x multiply by the Ocular lens 10x

4x multiply 10x = 40x

Convert 500 microns into mm (millimeters)

500 mm = 500./1000 = 0.5

Suppose you were told that the resolving power of the compound microscope is 0.0002mm? (0.2 microns) Explain what this means.

Any closer together we can't distinguish without the use of a lens that increases our resolving power.

3. General type of microscope: Compound Light Microscope (Transmitted light)

Are the most common and will be the type used in this laboratory. The compound microscope is made of two lenses, or lens systems, in series with each other: The ocular lens , which is located in the eyepiece, and the objective lens, which is located in the revolving nosepiece.

1. General type of microscope: Dissecting or Binocular Light microscope (reflected light)

Are used for viewing relatively large opaque objects such as plants, insects, and other small animals.

2. General type of microscope: Electron microscopes TEM = Transmitted electron beam

Are used in research laboratories and are powerful enough to show the crude structure of some large molecules like proteins.

Moving the slide to the right. Which way does the "e" appear to move?

Opposite direction

0.2 microns - Explain what this means

Any closer together we can distinguish without the use of a lens that increases our resolving power.

Calculate the Low power objective lens 10x multiply by the Ocular lens 10x

10x multiplied by 10x = 100x

Convert 2.2 mm into microns.

2.2 x 1000 = 2,200

If the total magnification of an object viewed is 200x and the objective lens is 40x, what is the magnifying power of the ocular lens?

20x

Supposed you looked at an object through a microscope and the image appeared 220 times larger than the actual object. How would you write the total magnifying power of the microscope?

20x

Why are the microscope lenses cleaned only with lens paper and special cleaning solution?

Because it's softer and it won't scratch it. Also, our fingers contain oils.

High Power Objective Lens (40x)

Magnifies the object being observed and produces an image within the microscope

Low Power Objective Lens (10x)

Magnifies the object being observed and produces an image within the microscope

Scanning Objective Lens (4x)

Magnifies the object being observed and produces an image within the microscope

Calculate the Total Magnification

Multiply the power of the ocular lens by the power of the objective lens

Light source

Provides illumination

Coarse Focus Knob

Raises and lowers the stage to bring the specimen into view and focus on it.

Fine Focus Knob

Raises and lowers the stage to refine the focus.

Iris diaphragm

The condenser has a built-in Iris Diaphragm that controls the amount of light passing through the specimen. The opening of the Iris Diaphragm is controlled by a lever.

Why is it necessary for the specimen to be thin when using the compound microscope?

The specimen has to be thin as light must be transmitted through an object and into the objective lens for it to be visible in a compound microscope.

Three general types of Microscopes

• Dissecting microscopes • Electron microscopes • Compound microscopes