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A factory has a motor that behaves like a resistor and an inductor in series, but their values are unknown. The motor is connected to a power source of 120 V. Using a multimeter, we can measure that the current in the source is 1.4 A. Using a wattmeter, the reading from the power source is 150 Watts. Complete the following table for the circuit.

E1 R1 L1
voltage
current
resistance
reactance
impedance
capacitance
power(true)
reactive power
apparent power
power factor

User Keul
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1 Answer

2 votes

Final answer:

By using the given voltage, current, and power readings, we can calculate the impedance, power factor, resistance, reactance, reactive power, and apparent power for the motor circuit, as well as determine that the capacitance is zero.

Step-by-step explanation:

The student is tasked with analyzing a motor circuit that behaves like a resistor and inductor in series connected to a 120 V power source. With a measured current of 1.4 A and power consumption of 150 Watts, we can fill in the table for the circuit.

First, let's calculate the impedance (Z) of the circuit using the formula Z = V/I, where V is the voltage and I is the current.

Z = 120 V / 1.4 A = 85.71 Ω

Now, let's determine the power factor (pf), which is the ratio of true power to apparent power. It can be calculated using the formula pf = true power / (V * I).

pf = 150 W / (120 V * 1.4 A) = 0.8929

We can then calculate resistance (R) using the formula R = Z * pf.

R = 85.71 Ω * 0.8929 = 76.5 Ω

To find the reactance (X), we use the formula X = Z * sqrt(1 - pf^2).

X = 85.71 Ω * sqrt(1 - 0.8929^2) = 36.53 Ω

The reactive power (Q) can be calculated using the formula Q = V * I * sqrt(1 - pf^2).

Q = 120 V * 1.4 A * sqrt(1 - 0.8929^2) = 80.43 VAR

The apparent power (S) is the product of the voltage and the current, S = V * I.

S = 120 V * 1.4 A = 168 VA

Since the motor behaves as a resistor and inductor, it does not have capacitance, so this value would be zero.

User Ericcurtin
by
7.4k points