Unlike the idealized ammeter described in Section 25.4, any real ammeter has a n

Question

Unlike the idealized ammeter described in Section 25.4, any real ammeter has a nonzero resistance. An ammeter with resistance RA is connected in series with a resistor R and a battery of emf E and internal resistance r. The current measured by the ammeter is IA.

PART A:

Find the current through the circuit if the ammeter is removed so that the battery and the resistor form a complete circuit. Express your answer in terms of IA, r, RA, and R. The more "ideal" the ammeter, the smaller the difference between this current and the current IA.

I=?

Explanation / Answer

equivalent resistance

Req =RA +R +r

so current through the circuit is

IA=E/(RA+R+r)

E=IA*(RA+R+r)

if ammeter is removed

Req =R+r

current through the circuit is

I=E/RA+r

I =IA*(RA+R+r)/(R+r)

I=IA*[1 +(RA/r+R)]

Related Questions

Navigate

• Browse (All)
• Browse U
• Subjects

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