[amp_mcq option1=”one voltmeter and one ammeter” option2=”one voltmeter, one ammeter and one wattmeter” option3=”one voltmeter, one ammeter and one energy meter” option4=”any of the above” correct=”option1″]
The correct answer is: A. one voltmeter and one ammeter.
To calculate the power factor of a single phase load, you need to know the voltage and current. You can measure these with a voltmeter and an ammeter. The power factor is then calculated as:
Power factor = cos(phi) = V/I
where V is the voltage and I is the current.
Option B is incorrect because you do not need a wattmeter to calculate the power factor. Option C is incorrect because you do not need an energy meter to calculate the power factor. Option D is incorrect because only option A is correct.