EE - AC Circuits

The power factor of a load connected to a 120V, 60 Hz supply is raised from 0.707 to 0.866 lagging by connecting a 53 µF capacitor across the load. What is the true power of the load in watts?

A 220 V, 10 hp, 60 Hz, single phase induction motor operates at an efficiency of 86% and power factor of 90%. What capacitance of capacitor in µF should be connected across the motor terminals in order to bring the total power factor to unity?

A series circuit consists of C = 30 µF and R = 50 ohms are connected across 110 V, 60 Hz source. Find the voltage across C in volts.

Two impedances Z1 = 10 + jX and Z₂ = R + j0, all in ohms are connected in parallel. Find the value of X in ohms so that the total impedance is 8 + j4 ohms.

An unbalanced wye-connected load with impedances of Za = 10 + j5 ohms, Zb = 8 + j4 ohms and Zc = 20 + j20 ohms is supplied by a 3 phase, 4-wire abc system. If the line to neutral voltage is 120 V, find the total power in watts.

Three 100μF capacitors are connected in delta to a 500 volt, three phase 50 HZ supply. Find the line current.

A 25 ohm resistance has an average power of 400 watts. Determine the maximum value of the current function if it is triangular.

A series RLC circuit has R = 10Ω, L = 40 x 10^-6 H and C = 60 x 10^12 F. What is the resonant frequency of the circuit in MHZ?

A parallel branch circuit composed of a 100 ohm resistance, 150 ohm capacitance reactance and 90 ohm inductive reactance. What is the total impedance of the circuit?

A 200 ohm resistor, a 0.04 henry inductor and a 0.25 microfarad capacitor are connected in series. What is the voltage across the combination if the current of 10 + j10 ma is applied at ω = 10,000 rad per second?

A resistance of 30 is in series with inductance of 30 mH. What is the frequency in hertz (HZ) so that the power factor angle is 60° lagging?

A coil of 0.1 H inductance and 4Ω resistance is connected in series with a 70.4 μF capacitor. What is the voltage across the inductor when the supply is 240v, 60 Hz?

A parallel RLC circuit has a resonant frequency of 20,000 rad/sec. If C is equal to 1 μF, find the value of L.

A sinusoidal current having peak value of 7.07 A is superimposed in dc of 5 A. If a hotwire ammeter is used to measure the combined current in the circuit, it will indicate__ amperes.

A balance wye-connected load of 30 + j10 ohms per phase is connected to a 3 phase 60 HZ 208 volts supply. Determine the value of each capacitor in mF which will yield unity power factor.