Equivalent Resistance


This circuit produces an output voltage, Vo, that is proportional to the input current, Is. The output voltage is measured using a voltmeter. The input current is the current of the current source. The constant of proportionality is called the equivalent resistance of the circuit consisting of R1, R2 and R3. The value of the equivalent resistance is determined by the values of R1, R2 and R3.


The values of the resistances R1, R2 and R3 can be adjusted using the scroll bars.



Challenges:

  1. Set R1 = 20 and R2 = 40. Predict the value of R3 required to cause Vo = 20. Use the scrollbars to check your prediction.

  2. Set R1 = 20 and R2 = 40. Determine the range of output voltage that can be obtained by adjusting the resistance R3.

  3. Set R1 = 25 and R3 = 40. Predict the value of R1 required to cause Vo = 30. Use the scrollbars to check your prediction.

  4. Set R1 = 25 and R3 = 40. Determine the range of output voltage that can be obtained by adjusting the resistance R2.

  5. Set R3 = 50. Determine the range of output voltage that can be obtained by adjusting the resistances R1 and R2.

  6. Determine the range of output voltage that can be obtained by adjusting the resistances R1, R2 and R3.

  7. Adjust R1, R2 and R3 so that Vo = 25.

  8. Adjust R1, R2 and R3 so that Req = 25.

  9. Adjust R1, R2 and R3 so that Req = 60.