Measurement of Voltage, Current and Power and Power Factor in a R-L series circuit

Experiment No.: 7

Experiment Name:

Measurement of Voltage, Current and Power and Power Factor in a R-L series circuit.


To measure the voltage, current, power and power factor in a R-L series circuit.


As per shown circuit diagram, we have used a 200 Watt incandescent lamp as resistive load (R) connected in series with a ballast of fluorescent lamp as an inductive load (L) as resistive load.

An MI type ammeter is connected in series with the load to measure the current flowing through it. We have selected the ammeter according to the load current. An MI type voltmeter is connected across the load to measure the voltage across it. To measure the power drawn by the load we have connected a wattmeter. And to measure the load power factor we have used a Power Factor meter.

In Wattmeter, the multiplying factor (MF) is given by,

In our case, MF= (300×10×1)/1500 = 2

So, we have to multiply 4 with the reading taken from the Wattmeter.

Circuit Diagram:

Observation Table:

Sl. No.Resistance (Ω)Inductance (mH)Voltage (V)Current (A)Power (W)Power Factor (cos φ)

Apparatus Used:

Sl. No.Name of the ApparatusQuantitySpecificationMaker’s Name
 1.Incandescent Lamp 200 W, 240 V Phillips
 2.Choke Coil 40 W, 240 V Intex 
 3.Single Phase
0-750-1500-3000 W,
300 V, 10 A, EDM type
4. Single Phase
Power Factor Meter 
 10.5 lag – 1 – 0.5 lead MECO-G 
 5. Voltmeter 10 – 300 – 600 V, MI typeMECO-G
6.Ammeter 10 – 5 – 10 A, MI typeK.E.W.
7.Single Phase Variac 1240 V / 0 – 270 V


The reading of wattmeter is too low to read accurately.

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