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Evaluate: Inverse-square Law

Test your knowledge:

  1. If you double the distance away from a radiation source what happens to the radiation counts?
  2. If the Average Counts is 1000 and you double the distance, how does the number of counts change?
  3. If the Average Counts is 900 and you triple the distance, how does the number of counts change?
  4. You are 10 km away from the town of Chernobyl having a picnic with your friends. You check your radiation detector and it says 900 counts. But, 100 is the safe level (oh dear)!! How far away do you tell your friends you need to be to be safe?
  5. Why do solar panels on Mars need to be larger than on the Earth?
  6. A solar power cell on a NASA space probe produces 1000 Watts of power when it leaves the Earth. If the space probe needs 10 Watts to keep functioning, how far can it go before it stops working? Hint: the Earth is 150 million km from the Sun, or 1 AU (Astronomical Unit).
  7. Mars is at 1.5 AU from the Sun, Jupiter 5.2 AU and Saturn 9.5 AU. Can the space probe in question 6 make it to Saturn?