Consider the circuit diagram at the right of the picture. The voltmeter is in pa
ID: 2281249 • Letter: C
Question
Consider the circuit diagram at the right of the picture. The voltmeter is in parallel with the light bulb (the circuit element) and the ammeter is in series with the light bulb. Suppose that you remove the voltmeter and replace it with either (i) a bare wire, (ii) another light bulb, or (iii) a broken wire as shown below.
The picture for this problem is located here ..... http://tinypic.com/r/33nzwc5/8
1)If you wanted to keep the ammeter reading essentiall the same as before, which would be the best choice? Explain.
2) On the bases of your answer above, what is the desired resistance of the voltmeter (large or small relative to the resistance of the bulb)? Explain.
3) Along similar lines, what is the desired resistance of the ammeter?
Explanation / Answer
1) the best choice would be to replace the voltmeter with the broken wire. Voltmeters are devices attached parallel to elements and are designed so that theyhave very high resistance so that the current in the orriginal circuit is not distured, Thus the broken wire (which has infinite resistance) works like an ideal voltmeter.
2) The desired resistance of the voltmeter is infinite. (ie like open circuit)
3) The desired resistance of ammeter should e zero, because they are attached in series to the circuit and to prevent their effect on the circuit, resistance should be as low as possible