Microscopes: parts, types and total magnification
Grade 9 Science Worksheet - Challenge Me
Circle the best answer.
Read this first
Field of view (example data)
total magnification field diameter (mm) 100× 1.8 400× 0.45 At 100× Ari counts 128 evenly spread cells in the field. About how many cells will the 400× field show?
- About 2,048 cells, since 400× shows 16 times more
- About 8 cells
- About 32 cells, since the field is 4 times narrower
- About 512 cells, since 400× is 4 times more
Use π ≈ 3.14. Esme estimates the cells on the whole cover slip. About how many are there?
- About 3,600 cells, from 9 × 400
- About 8,000 cells, from 9 ÷ 0.45 per mm
- About 23,000 cells
- About 5,700 cells, using 0.45 as the radius
Photo magnification 500×. The cell measures 8 mm on the photo. Note: 8 mm × 500 = 4,000 mm. Jun checks a classmate's note. Which fix is right?
- Keep the multiplying, but convert: 4,000 mm is 4 m long
- Divide, but keep the unit: the cell is 16 mm
- Ignore the magnification: the cell is 8 mm long
- Divide, not multiply: 8 mm ÷ 500 = 0.016 mm = 16 µm
“Example data:” Kira sized a cell on a poster copy using the original photo's bar. Which result is right?
- 216 µm, multiplying 36 by 6
- 3.6 µm, using the poster copy's own 60 mm bar
- 1.8 µm, halving the answer for the enlargement too
- 7.2 µm, using the original 30 mm bar
“Three ways a figure can show size (example data):” A figure will be resized for a poster. Luz wants a size reading that stays correct. Which feature should the figure carry?
- A note naming the objective lens used, such as 40×
- The date on which the photo was taken
- A scale bar drawn inside the picture, so it resizes with the picture
- A magnification label such as 400×, printed under the picture by the camera
1 nm = 1,000 pm. A headline says a new light microscope at 20,000× shows single atoms, about 0.1 nm wide. Milo checks the table. Which reply is best?
- Possible: 0.1 is smaller than 200, so atoms are easy to separate with enough light
- Possible: 20,000× is far more than the 400× in the table, so atoms would show
- Not possible: light microscopes cannot go above 400×, whatever lens is used
- Not possible: light microscopes cannot separate points closer than about 200 nm
Published width: about 8 µm. 1 mm = 1,000 µm. Noah finds the real width of red blood cells from the photo. Which statement is best supported?
- The real width is about 1,296 µm, the mean photo width times the 400× power
- The real width is about 0.0081 µm, since 3.24 ÷ 400 is 0.0081 and the unit is µm
- The mean photo width is 3.24 mm, so the real width is about 8.1 µm, close to 8 µm
- The real width is 3.24 µm, the mean width as measured on the photo itself
Two electron microscopes (facts from OpenStax Biology 2e)
kind how the beam works what it shows scanning moves back and forth across the surface surface details transmission passes through a thin slice internal structures A caption says a scanning electron micrograph shows the mitochondria inside a cell. Ren checks the card. Which reply is best?
- Doubtful: electron microscopes cannot show organelles in a cell, just whole cells in total, at most
- Right: scanning means the beam scans through the whole cell from top to bottom
- Doubtful: scanning images show surface details; insides need a transmission image of a slice
- Right: electron microscopes show the inside of any cell they are used on
1 mm = 1,000,000 nm. Tala assumes the eye can separate points 0.2 mm apart on the image. A lens resolves 200 nm. About what total magnification is the most useful?
- About 100,000×, the most an electron microscope reaches
- About 40,000,000×, from 200,000 × 200
- About 1,000×, since 200,000 nm ÷ 200 nm is 1,000
- About 1×, since 0.2 and 200 are close
1 mm = 1,000 µm. Zee reads a cell as 20 mm long, with a ruler good to ±1 mm. What range of real lengths is fair?
- 38 to 42 µm
- 9,500 to 10,500 µm
- 39.9 to 40.1 µm
- 38 to 42 mm
