Physics and Astronomy

Black Box Mystery

The Black Box Mystery event is composed of two activities related to electrical circuits.

  1. Teams will be given a series of simple electrical circuit diagrams for which the teams must predict whether or not a light bulb will light up if certain switches will be open or closed.
  2. Teams will be provided with a sealed black box with three single-pole, single-throw switches. The way in which the switches are wired is hidden. Teams will also receive an identical unwired open box which will have to be wired in the same way the black box is wired.
Purpose To learn some circuit theory.
Participants Teams of two or three.
  1. Each group must provide eight pieces of insulated bell wire each 10 cm long with bared ends
  2. A small flat-headed screwdriver with a blade no larger than 5 mm.
  3. A simple "circuit tester": Pre-wire a battery and bulb assembly as shown in the diagram below. Any type of battery and bulb may be used, but care should be taken to insure that the battery is fresh and that the bulb is compatible with the voltage of the battery! The loose leads should be at least 10 cm long.
  1. Each group will be provided with a wired Black Box containing three switches and an identical unwired switch box.
  2. Detailed instructions for each group will be provided in a sealed envelope which must not be opened until the starter calls "time".
  3. Contestants must not break or damage the seal in their mystery circuit box.
  4. Both part A and part B of the event must be handed in together to receive bonus for speed.
  5. If the event is not completed within 30 minutes, marks will be awarded for partial completion.
  1. Electrical Circuit Diagrams (16 points)
  2. Observation and Circuit Diagram (13 points)
  3. Completed Black Box Circuit (5 points)
  4. Fastest Time of Completion: 1st (6 points); 2nd (4 points); 3rd (2 points)
  5. Note: 34 points out of 40 will be awarded for successful completion of this event. Up to 6 points will be awarded for speed of completion.
Source Youth Science Foundation Science Olympics Manual.


Circuit Tester

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