The Microscope The Microscope n Simple Microscope one

The Microscope

The Microscope n Simple Microscope – one lens n Ex – Magnifying lens n Compound Microscope – 2 lenses that “compound” or magnify each other. n Dissecting Microscope – no special slide preparation

Microscopes

Parts of The Compound Microscope

Continued… n Eyepiece: n Magnifies material being viewed by 10 X n The part of the microscope you look into n Sometimes contains a pointer that can be seen as you look into the eyepiece. n May also be called the ocular.

Continued… n Nose piece: n Part of microscope to which the objectives are attached n Rotates to allow for the changing of objectives to increase or decrease magnification.

Continued… n Arm: n A secure part of the microscope to hold on to when the microscope is being carried.

Continued… n Objectives: n Low (4 x) n Medium (10 x) n High (40 x)

Continued… n Stage: n Platform on which microscope slide rests n Mechanical Slide Adjuster n Used for adjusting the position of the slide for viewing

Continued… n Coarse adjustment knob: n Large movements of the stage n Fine adjustment knob: n Precise focusing under High power

Continued… n Diaphragm: n regulates the amount of light passing through the slide

Continued… n Illuminator n Light source n Base: n provides support for microscope

Continued… n Body tube: n Connects Ocular to Nosepiece

TOTAL MAGNIFICATION n Power of the eyepiece (10 X) multiplied by objective lenses determines total magnification.

Magnification Objective Ocular Total Eyepiece Magnification Low Power 4 x 10 x 40 x Medium Power 10 x 100 x High Power 40 x 10 x 400 x

Field of View n Field of View (FV) is the illuminated circle that you see when looking through the ocular eyepiece. n If we know the diameter of the FV then we can estimate the size of our microorganisms.

Field of View n With our microscopes the diameter of the FV under low power is 4 mm n FV is measured in micrometers or microns. n 1 mm = 1000 microns n Therefore, our FV under low power is 4000 microns

Using the Field of View to Estimate Microscopic Measurements If an organism takes up ½ of the FV under low power, it must be about 2000 microns in length

How does the FV change as Magnification goes Up? ? n As magnification goes up, the size of the FV gets smaller. n If magnification increases 2 x, the FV is divided by 2 x, or 2 x smaller. n If we switch from low power (4 X) to medium power (10 X), the increase in magnification is 2. 5 times (10 X/4 X). n The FV under medium power will be 1600 microns (4000/2. 5)

Calculating the Diameter of the Field of View n Step 1 Calculate the Increase in Magnification. New Objective n Old Objective n Step 2 Divide the old F of V by the increase in magnification calculated in Step 1 n Old F of V (Microns) n Increase in Mag n

To Calculate the Changing FV n Low – 5 x; Med – 10 x; High – 50 x n Low FV = 5 mm (1000 um x 5 mm= 5000 um) n Step 1 – Calculate the increase in Magnification n Ex – 10 x/5 x = 2 n Step 2 – Calculate the reduction of the FV n 5000 um/2 = 2500 um

Let’s try High Power n Step 1 n Step 2 – 50 X

Electron Microscopy n SEM n TEM