Potential difference and internal resistance?
A voltmeter with an internal resistance of 10000 ohms is connected in parallel to R3 as shown in the picture below. What potential difference does it show?
http://i53.tinypic.com/4kzh4h.jpg
Thanks in advance.
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the resistance in the parallel resistors R2 and R3 combined = R2R3/(R2+R3) which we can call R2&R3
the voltage across this is proportional to what fraction of the total resistance of the circuit represents
so V/12 (Ratio of Voltage across parallel / Total Voltage) = (R2&R3)/(R2&R3 + R1)
this is true as V=iR, and the current across 2 and 3 combined is the same as 1