The Basics of Resistance

  1. Start with a graphite pencil line about 5 cm long and 3 mm wide. Repeatedly draw on the line until it is completely dark. Use the multimeter to measure its resistance, in ohms, W. Lay the probe on its side, instead of using its endpoint.
  2. What variables, do you think, affect resistance? Design a plan to test for each factor that you listed.

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    Variables

    How you will test it:

    Your results:

    A: _________

     

     

     

     

    		  

    B: _________

     

     

     

     

    		  

    C: _________

     

     

     

     

    		  

    D: _________

     

     

     

     

    		  

    E: _________

     

     

     

     

    		  

     

    Combine your results into one relationship for resistance and the variables upon which depends.

    ____________________________

  3. If you have time, compare the resistivity, s, of graphite with pencil "lead" (graphite mixed with clay), crayons, silver ink, etc.

    4.  

     

     

  4. Use graphite lines to derive relationships for resistors in series and in parallel. (Draw them separately, then fill in the connection between the lines.)

Series:

Parallel: