Voltage of battery through voltmeter

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SUMMARY

The discussion focuses on calculating the voltage reading of an 85 V battery with an internal resistance of 5.73 ohms when measured with a voltmeter of 482 ohms resistance. The voltmeter reading is determined by treating it as a resistor and calculating the current to find the potential drop across it. Additionally, the maximum ratio of internal resistance to voltmeter resistance is explored to ensure the error in the emf reading does not exceed 5%. The participants successfully derived both answers using the equations V=IR and V=E-Ir.

PREREQUISITES
  • Understanding of Ohm's Law (V=IR)
  • Knowledge of internal resistance in electrical circuits
  • Familiarity with voltmeter operation and resistance
  • Ability to manipulate equations involving voltage and current
NEXT STEPS
  • Calculate voltage readings using different resistor values in series with a battery
  • Explore the impact of internal resistance on battery performance
  • Learn about error analysis in electrical measurements
  • Investigate the design and function of voltmeters
USEFUL FOR

Students studying electrical engineering, physics enthusiasts, and anyone involved in circuit analysis or battery performance evaluation.

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Homework Statement



A 85 V battery has an internal resistance of r = 5.73 ohms .

(a) What is the reading of a voltmeter having a resistance of R_v = 482 ohms when placed across the terminals of the battery?
___________ V
(b) What maximum value may the ratio r/R_v have if the error in the reading of the emf of a battery is not to exceed 5.0%?


Homework Equations



V=IR
V=E-Ir
V_v= I_fs ( R_c +R_s)

The Attempt at a Solution



i don't know where to start, the only thing i have tried was drawing the diagram of the circuit. please offer input on where to start thank you in advance
 
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(a) Just treat the voltmeter as a resistor. Then find the current and calculate the potential drop across the voltmeter.

(b) For this let the resistance of the voltmeter be R. Then using the same method above, determine the potential drop across the voltmeter in terms of R, f(R). Then we want 0.95(V)<|f(R)|<1.05(V) where V is the emf of the battery.
 
thank you very much i got both answers correct thank you
 

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