Questionable resistance pictures included

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SUMMARY

The discussion centers on determining the appropriate circuit for measuring battery voltage while supplying a current of 6A. Circuit a is identified as the preferred choice due to its lower resistance. Calculations reveal that the current flowing through the headlight in both circuits is 2.4e-4 A when the voltmeter is connected, while the headlight initially draws 6A. The resistance of the headlight is significantly lower than that of the voltmeter, which is designed to minimize current draw during measurement.

PREREQUISITES
  • Understanding of Ohm's Law (V = IR)
  • Knowledge of voltmeter specifications and functionality
  • Familiarity with circuit analysis concepts
  • Basic electrical resistance calculations
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Homework Statement


You would like to check if the battery voltage drops while it is supplying a current of 6A. You use a voltmeter designed to measure voltages up to 20V and having a resistance of 50,000 Ohms. Which of the two circuits below should be used?
a.) How much current (in A) would flow through the headlight for Circuit a?
b). How much current (in A) would flow through the headlight for Circuit b?

OA-Voltmeter.jpg




Homework Equations


delta(V) = IR


The Attempt at a Solution



Circuit a should be used because it has the least resistance.

a.) I = 12/50000 = 2.4e-4
b.) I = 12/50000 = 2.4e-4
 
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Before putting the voltmeter into the circuit the current passing in the headlight is 6 amps.
What is the resistance of the headlight?
How does that compare to the resistance of the voltmeter?

The purpose of a voltmeter is to measure a voltage while actually disturbing that voltage as little as possible. Voltmeters are designed to draw as little current as possible.

Now consider which diagram is appropriate.
 
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