An electric motor, under load, has an effective resistance of 30 $\Omega$ and an inductive reactance of 40 $\Omega$ . When powered by a source with a maximum voltage of 420 V, the maximum current is:
A) 6.0 A
B) 8.4 A
C) 10.5 A
D) 12.0 A
E) 14.0 A

Question

An electric motor, under load, has an effective resistance of 30 $\Omega$  and an inductive reactance of 40 $\Omega$ . When powered by a source with a maximum voltage of 420 V, the maximum current is:
A) 6.0 A
B) 8.4 A
C) 10.5 A
D) 12.0 A
E) 14.0 A

Quizplus · Accepted Answer

To find the maximum current, we need to calculate the impedance (Z) of the motor using the given information.

Z = √(R² + Xl²) where R is the resistance and Xl is the inductive reactance

Z = √(30² + 40²)

Z = √(900 + 1600)

Z = √2500

Z = 50 Ω

Now, we can use Ohm's Law to find the maximum current:

I = V/Z where V is the maximum voltage

I = 420/50

I = 8.4 A

Therefore, the answer is B) 8.4 A.

An Electric Motor, Under Load, Has an Effective Resistance of 30