A circuit you 're building needs an ammeter that goes from 0 mA to a full scale reading of 50 mA Unfortunately, the only ammeter in the storeroom goes from 0A to a full scale reading of only 500A Fortunately, you 've just finished a physics class, and you realize that you can make this ammeter work...

Model Assume ideal connecting wires Visualize Because the ...

A circuit you're building needs an ammeter that goes from 0 mA to a full-scale reading of

Question:

A circuit you're building needs an ammeter that goes from 0 mA to a full-scale reading of 50 mA. Unfortunately, the only ammeter in the storeroom goes from 0μA to a full scale reading of only 500μA. Fortunately, you've just finished a physics class, and you realize that you can make this ammeter work by putting a resistor in parallel with it, as shown in FIGURE P28.57. You've measured that the resistance of the ammeter is 50.0Ω , not the 0Ω of an ideal ammeter.

a. What value of R must you use so that the meter will go to full scale when the current I is 50 mA?
b. What is the effective resistance of your ammeter?