the voltage meter has some resistance and as such will always allow some current
ID: 3307634 • Letter: T
Question
the voltage meter has some resistance and as such will always allow some current to flow....
The voltage meter has some resistance and as such will always allow some current to flow. How would it affect your data if the resistance used in the circuit were near to the resistance in the voltmeter (i.e. voltage sensor)? If you had a current sensor (ammeter) instead of a voltmeter, how could we get the same data without using a voltmeter? Be specificl Do you think it would be easier or more complicated? Would it be more or less accurate? Draw a circuit that uses the ammeter with the location of the ammeter shown.Explanation / Answer
Ok So let's Start with the first parts,
a)
The voltmeter is always connected in parallel with the component under test. Thus, any current through the voltmeter will contribute to the overall current in the tested circuit, affecting the voltage being measured.
A perfect voltmeter has infinite resistance, in such a way it draws no current from the circuit under test (no current passes through it). The voltmeter’s own resistance alters the resistance ratio of the voltage divider circuit, consequently affecting the voltage being measured.
In the present case you'll have half of the main current through the circuit passing through your voltmeter (its resistance: RV/R/2); the voltage measured by the voltmeter will be: U(V)=IR/2, with I=initial current through the resistor of interest.
There are good practical solutions to this problem.
b)
The ammeter is always connected in series with the component under test. In comparison with the voltmeter, the ideal ammeter has zero internal resistance (it has to drop as little voltage as possible when the current passes through it). If it has a resistance, the measured intensity will be lower than the 'real ' one.
If RA=R, the intensity will he half than the intensity before introducing the ammeter in the circuit. (Need full question with figure to draw circuit of ammeter.)
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