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I must find the voltage indicated by the voltmeter for the circuit below:
R2 || R1
I=E/(R1+R2||R1)=3.746 *10^-6 A
So the voltage indicated by the voltmeter is I*(R2||R1)=8.243 V
And, if the voltmeter is ideal, the voltage should be 7.5 V.
Did i make any mistakes???
And I want to ask you one more thing. I'm a bit confused about this circuit. I learned that when you want to use a voltmeter you put it in ||, but in this figure, it's considered to be in || with R1 and in fact it indicates the voltage PT2??? Can anybody help?
If you add these two voltages together you will get 15volts, but the two voltages should be the same at 7.5volts each using an ideal voltmeter. Later in your studies you will find other ways for making these calculations where typically the internal resistance of the voltmeter is not considered. You only need to consider the internal resistance if it is low enough, compared to the resistances of your circuit, to make a difference. In this case a 10Meg meter and 2.2Meg resistors in the circuit did make a difference. If the circuit had 2.2Kilohm resistors it would have not make much difference and the voltages would have been much closer to 7.5volts across each resistor.
As to your last question, the voltmeter is in parallel with R2 and is reading the voltage across R2.