Chapter 27, Problem 051 In the figure a voltmeter of resistance Rv-348 ? and an

Question

Chapter 27, Problem 051 In the figure a voltmeter of resistance Rv-348 ? and an ammeter of resistance RA-3.07 ? are being used to measure a resistance R in a circuit that also contains Ro-100 ? and an ideal battery of emf ? = 12.0 v. Resistance R is given by V/ì, where V is the potential across R and i is the ammeter reading. The voltmeter reading is V, which is V plus the potential difference across the ammeter. Thus, the ratio of the two meter readings is not R but only an apparent resistance R,-V/i. If R = 120 ?, what are (a) the ammeter reading in milliamperes, (b) the voltmeter reading, and (c) R? Ro (a) Number (b) Number (c) Number Units Units Units

Explanation / Answer

As per the given diagram, the total circuit resistance = 100 + (120 + 3.07) // (348)
=100 + (123.07*348) / (123.07+348)

= 100 + 42828.36 / 471.07 = 190.9 ohm

So, current from battery = 12 / 190.9 = 0.063 A

Voltage drop across Ro=100*0.063 = 6.30 V

therefore, voltmeter reading = 12 - 6.30 = 5.70 V

Current through the ammeter = 0.063 * 348 / [123.07 + 348)] = 0.0465 A

And, R' = 5.70 / 0.0465 = 122.6 ohm

therefore -

(a) 0.0465 A = 46.5 mA

(b) 5.70 V

(c) 122.6 ohm.

Related Questions

Navigate

• Browse (All)
• Browse C
• Subjects

---

---

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