1. You are an electrican working on a industrial plant. A circuit contains eight
ID: 1834101 • Letter: 1
Question
1. You are an electrican working on a industrial plant. A circuit contains eight incandescent lamp connected in series across 480v. one lamp has burned out and you must determine which one is defective. you have available a voltmeter, ammeter, and ohmmeter. which meter would you use to determine which lamp is defective in the shortest possible time? Explain how you would use this meter and why2.two resistors are connected in series. one resister has a resistance of 1000-ohm, and the other resister value is not known. the circuit is connected to a 50-v power supply, and there is a current of 25ma flowing in the circuit. if a 1500-ohm resister is connected in parallel with the unknown resister, how much current will flow in this circuit
Explanation / Answer
if one lamp is burnt then the current through the circuit is 0.there is no use of ammeter.
if there is no current flow ,Voltmeter cant be used which depends on current for its measurement.So we can use only Ohm meter which indicates the change in Resistance of the burned element.
50V/25mA = 2K is the net resistance.Thus the other resistance is 1K.Now the 1.5K is connected in parallel with 1K which will give equivalent resistance as
(1.5 II 1)K = 600 .so ,the current in the circuit now is 50V/1.6K = 31.25mA.
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