A circuit you're building needs an ammeter that goes from \(0 \mathrm{~mA}\) to a full-scale reading of \(50.0 \mathrm{~mA}\). Unfortunately, the only ammeter in the storeroom goes from \(0 \mu \mathrm{A}\) to a fullscale reading of only \(500 \mu \mathrm{A}\). Fortunately, you can make this ammeter work by putting it in a measuring circuit, as shown in Figure P23.66. This lets a certain fraction of the current pass through the meter; knowing this value, you cân deduce the total current. Assume that the ammeter is ideal.

a. What value of \(R\) must you use so that the meter will go to full scale when the current \(I\) is \(50.0 \mathrm{~mA}\) ?

b. What is the equivalent resistance of your measuring circuit?

R A -Your measuring circuit 500 A ammeter 50.0 2 FIGURE P23.66