Element 3-13 Power Relationships

Question 1

What does the power factor equal in an R-L circuit having a 60 degree phase angle between the voltage and current?

Answer 1

0.5

Question 2

If a resistance to which a constant voltage is applied is halved, what power dissipation will result?

Answer 2

double

Question 3

746 watts, corresponding to the lifting of 550 pounds at the rate of one foot per second, is the equivalent of how much horsepower?

Answer 3

one horsepower

Question 4

in a circuit where the ac voltage and current are out of phase, how can the true power be determined?

Answer 4

multiplying apparent power times the power factor

Question 5

what does the power factor equal in an R-L circuit having a 45 degree phase angle between the voltage and the current?

Answer 5

.707

Question 6

What does the power factor equal in a R-L Circuit having a 30 degree phase angle between the voltage and the current?

Answer 6

.866