U NDERSTANDING THE M ICROSCOPE

UNDERSTANDING MAGNIFICATION A microscope’s power refers to the amount of magnification. Power can be computed if you know the magnification of the eyepiece lens and the objective lens.

W HAT ’ S MY POWER ? To calculate the power of magnification, multiply the power of the eyepiece lens by the power of the objective. What’s my power?

T OTAL M AGNIFICATION : T O FIGURE THE TOTAL MAGNIFICATION OF AN IMAGE THAT YOU ARE VIEWING THROUGH THE MICROSCOPE IS REALLY QUITE SIMPLE. T O GET THE TOTAL MAGNIFICATION TAKE THE POWER OF THE OBJECTIVE (4X, 10X, 40 X ) AND MULTIPLY BY THE POWER OF THE EYEPIECE, USUALLY 10X. 4x objective lens 10x eyepiece 10x objective lens 10x eyepiece 40x objective lens 10x eyepiece

C OMPARING POWERS OF MAGNIFICATION What is the difference between magnifications? We can see better details with higher the powers of magnification, but we cannot see as much of the image. Which of these images would be viewed at a higher power of magnification ?

W HY ARE THE IMAGES NOT WHAT I WOULD EXPECT ? Letter “E”

W HY ? L IGHT TRAVELS IN A STRAIGHT LINE, BUT WHEN IT PASSES THROUGH THE MAGNIFYING LENS, IT REFRACTS ( CHANGES DIRECTION ), CAUSING THE IMAGE TO BE UPSIDE DOWN AND BACKWARDS. T HE FINAL IMAGE FORMED BY THE EYEPIECE LENS IS REVERSED AND MUCH LARGER THAN THE OBJECT BEING VIEWED. Image you see in the microscope is… Reversed (flipped left to right) and Inverted (flipped top to bottom)

W HAT DOES THIS MEAN FOR YOU ? When you nudge the slide you are studying away from you, the image will move towards you. When you push the slide a bit to the left, it will move to the right.

S HOULD WE TRY IT ?  What do I do when I get a turn at the microscope?  What should I do while I am waiting for a turn?

Have your partner read through the steps while you perform the operations. When you are done, switch roles. ~Steps for Microscope Viewing~ 1. Start with the lowest power objective lens. 2. Place your specimen on the middle of stage. 3. Use the coarse adjustment knob to bring the objective lens close to the slide. 4. Use the fine adjustment knob to focus the object. 5. Rotate the objective lens to a higher power and use the fine adjustment knob again. 6. Record your observations. Remember: Record exactly what you see. 7. Finished? Switch back to the lowest objective lens 8. Turn off the light.

W HAT DO I DO WHILE I AM WAITING FOR MY TURN ? Review the parts of the microscope Cut out the vocabulary cards for the parts of a microscope Challenge yourself to a game of concentration There will be a quiz on the parts of the microscope soon Students will be called back in pairs to view the “e” slides…listen carefully for your names Unsafe or improper behavior = immediate loss of privilege