Measuring Voltage Divider Output with Real Voltmeters

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SUMMARY

To measure the output of a voltage divider using real voltmeters with effective resistances, one must model the voltmeter as a finite resistance (Rv) rather than an ideal open circuit. The output voltage can be calculated using the formula Vout = (R2 / (R1 + R2 + (Rv * R2 / (R1 + Rv)))) * Vin, where Vin is the input voltage. This approach accounts for the loading effect of the voltmeter on the voltage divider circuit, providing a more accurate measurement of the output voltage.

PREREQUISITES
  • Understanding of voltage dividers and their operation
  • Knowledge of Ohm's Law and circuit analysis
  • Familiarity with the concept of effective resistance
  • Basic skills in using voltmeters and interpreting their readings
NEXT STEPS
  • Study the impact of loading effects on voltage measurements
  • Learn about the characteristics of different types of voltmeters
  • Explore circuit simulation tools to model voltage dividers with real components
  • Investigate the use of operational amplifiers to buffer voltage divider outputs
USEFUL FOR

Electronics students, electrical engineers, and hobbyists interested in accurate voltage measurement techniques in circuit design.

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Homework Statement



How do you measure the output of a voltage divider with real voltmeters that have effective resistances

Homework Equations





The Attempt at a Solution



I know that for an ideal voltmeter (one with infinite resistance), the voltage divider is R2/(R1+R2), but I don't know what to do when the voltmeters have effective resistances. Any help would be great!
 
Physics news on Phys.org
Instead of considering the voltmeter as an effective "open circuit" at the point of measurement, which is equivalent to an infinite parallel resistance, substitute it for (i.e. model it as) a finite resistance, say Rv.
 

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