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Integrated Coordinated Science for the 21st Century

Active Physics
+ Chapter 5
Long-Distance Communication
Answers
Physics To Go
  1. a) Answers will vary.
    b) Activity 3 showed how electricity can produce magnetism, how a coil can make the magnetism stronger, and how an electromagnet works.
  2. a) Answers will vary. If the students use an electromagnet, they can make it stronger by increasing the number of turns of wire or by using more batteries.
    b) Students might want a telegraph key for the sender. They might request a light and socket to provide a visual signal. They might also want a buzzer (which many stores sell).
  3. a) Railroad tracks provided a straight, level path already cleared or cut through mountains.
    b) The railroads needed to keep track of their trains.
  4. a) Answers will vary.
    b) See the code on p. 272. Students could indicate the end of a word by a pause in the stream of dots and dashes. A longer pauses, or “STOP”, could indicate the end of a sentence.
    c) It is a binary code, so the receiver need distinguish only a dot from a dash. The code represents letters, digits, and punctuation.
    d) Sending a message takes a long time. Decoding can be time-consuming as well.
    e) Find a way to store the received series of dashes and dots so they can be decoded and checked later.
  5. a) Use the code for a period, which is dot-dash-dot-dash-dot-dash.
    b) You could write “STOP.”
  6. a) Both are binary systems.
    b)
    Data Table
  7. Yes, by connecting wires to the telegraph line and hooking up another receiver.