Lesson 2: RP: Microscopes

Question 1

What is the eyepiece lens?

Answer 1

Where the viewer looks through to see the specimen

Question 2

What is the stage?

Answer 2

Where the slide is clipped down.
Some cells need to be stained with iodine before being clipped down

Question 3

What is the objective lens?

Answer 3

Changes the magnification of the image.

Question 4

What is the coarse focus knob?

Answer 4

Moves stage up and down

Question 5

What is the fine focus knob?

Answer 5

Used to make image clearer

Question 6

What is resolution?

Answer 6

Resolution is the ability to distinguish between 2 points on an image ie. the amount of detail.

Question 7

What is the mirror?

Answer 7

Reflects light from light source onto stage.

Question 8

What chemical is used to make the specimen clearer in a microscope?

Answer 8

The orange chemical iodine.
It turns blue/black on transparent, starchy specimens.

Question 9

What is the smallest magnification on the objective lens?

Answer 9

4x

Question 10

What is the largest magnification on the objective lens?

Answer 10

40x

Question 10

What is used to focus an image at a low magnification?

Answer 10

The coarse focus knob will focus an image at a low magnification.

Question 11

What is used to focus an image at a high magnification?

Answer 11

The fine focus knob is used to focus an image at a high magnification.

Question 12

What is the nosepiece?

Answer 12

The nosepiece will move the objective lens.

Question 13

What are the 8 steps to using a microscope?

Answer 13

1.) Put the slide onto stage. Stain transparent cells with iodine to make visible.
2.) Turn objective lens to lowest magnification.
3.) Turn coarse focus knob to ensure slide is ALMOST touching objective lens.
4.) Look down into eyepiece
5.) Increase distance between objective lens (using CFN) and slide until cells come into focus
6.) Bring cells into focus
7.) Increase objective lens magnification
8.) Use fine focus knob to bring cells into focus.

Question 14

Why do you start the objective lens on lowest magnification?

Answer 14

• To have a better field.
• View will be wider
• Increased number of cells seen.

Question 15

Why don’t you move the stage close to the objective lens?

Answer 15

• Prevents slide from breaking
• Prevents blurriness

Question 16

How do you calculate the overall magnification?

Answer 16

Overall magnification = eyepiece lensx objective lens

Question 17

How do you calculate the image size?

Answer 17

Image size = actual size x magnification

Question 18

What is the usual magnification for an eyepiece lens?

Answer 18

10x

Question 19

What is the image size?

Answer 19

What the object appears to be in the microscope.

Question 20

What is the actual size?

Answer 20

How big the object is in real life.

Question 21

Give a health and safety factor from the practical.

Answer 21

• Be careful with glass slide

Question 22

Give 2 ways you can improve this practical.

Answer 22

• Wear gloves: avoid cross- contamination
• Add few drops of water to avoid dehydration of cells (structures seen better.)

Question 23

What are the 3 different usual magnifications of objective lens?

Answer 23

• 4x
• 10x
• 40x

Question 24

Which one is smaller in size?
- Fine focus knob
- Coarse focus knob

Answer 24

• Fine focus knob is smaller
• (usually under the coarse focus knob)