Integrated Coordinated Science for the 21st Century
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Answers
Physics To Go
- a) In the photographic print, neither dots nor pixels can be seen.
b) The scanned and printed image would have dots.
c) Photographic slides can show more fine detail (there are no pixels).
- a) The one with the larger number of dots per cm, because it will print much finer detail.
b) It would be important for printing the curved portions of letters. However, 80 dots/cm is 8 dots/mm, which is good resolution (the same as a fax).
- a) 2.0 X 105
b) It is possible to place a ruler against the screen, look through a magnifier, and estimate the number of vertical lines per millimeter.
c) The computer image shows more detail.
d) The pixels are smaller.
- a) The greater the number of pixels per centimeter, the more detail can be shown on the image.
b) More, so the monitor can show more detail.
- a) The color image requires more, because it is made of red, blue, and green pixels. The color image requires three times more.
b) The video requires far more memory, because it is a sequence of still images.
- a) The messages can consist of a stream of ones and zeroes. These can be assembled into an image in the same way you did in this activity.
c) Radio would be a good choice.
d) The extraterrestrial would have to know that you set up a rectangular grid, where the starting point was, which way to begin filling in pixels, and when to “return” to the next row or column (and how to decode the message to convert radio signals to a stream of digital data).
- a) A fax takes about 30 s.
b) If the grid is 80 dots per centimeter, a full-page image has about two million dots.
c) 30 s
d) 2 X 106/30 = 7 X 104 ones and zeroes per second.
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