A circuit you are building needs an ammeter that goes from 0 mA to a full-scale

Question

A circuit you are 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 0 mu A to a full- scale reading of only 500 mu A. Fortunately, you have just finished a physics class, and you realized that you can make this ammeter work by putting a resistor in parallel with it, as shown in the Figure below. You have measured that the resistance of the ammeter is 50.0 ohm, not the 0 ohm of an ideal ammeter. What value of R must you use so that the meter will go to full scale when the current I is 50 mA? What is the effective resistance of your ammeter?

Explanation / Answer

r/50+r*50=0.5

50r=25+.5r

r=25*2/99=0.5 ohm


effective resitance=25/50.5=0.49 ohm

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.