Design a problem to help other students

If and calculate the instantaneous power and the average power.

Given the circuit in Fig. 11.35, find the average power supplied or absorbed by each element.

A load consists of a resistor in parallel with a capacitor. If the load is connected to a voltage source find the average power delivered to the load.

Using Fig. 11.36, design a problem to help other students better understand instantaneous and average power

Assuming that in the circuit of Fig. 11.37, find the average power delivered to each of the passive elements.

For the circuit in Fig. 11.38, Find the average power absorbed by the resistor. 50- is 6 cos 103 t A.

Given the circuit of Fig. 11.39, find the average power absorbed by the resistor.

In the circuit of Fig. 11.40, determine the average power absorbed by the resistor.

For the op amp circuit in Fig. 11.41, Find the average power absorbed by the resistor.

In the op amp circuit in Fig. 11.42, find the total average power absorbed by the resistors.

For the network in Fig. 11.43, assume that the port impedance is Find the average power consumed by the network when 33 sin(377t 22 ) mA.

For the circuit shown in Fig. 11.44, determine the load impedance Z for maximum power transfer (to Z). Calculate the maximum power absorbed by the load.

The Thevenin impedance of a source is while the peak Thevenin voltage is Determine the maximum available average power from the source.

Using Fig. 11.45, design a problem to help other students better understand maximum average power transfer

In the circuit of Fig. 11.46, find the value of that will absorb the maximum power and the value of the maximum power.

For the circuit in Fig. 11.47, find the value of that will receive the maximum power from the circuit. Then calculate the power delivered to the load .

Calculate the value of in the circuit of Fig. 11.48 in order for to receive maximum average power. What is the maximum average power received by ZL?

Find the value of in the circuit of Fig. 11.49 for maximum power transfer.

The variable resistor R in the circuit of Fig. 11.50 is adjusted until it absorbs the maximum average power. Find R and the maximum average power absorbed.

The load resistance in Fig. 11.51 is adjusted until it absorbs the maximum average power. Calculate the value of and the maximum average power.

Assuming that the load impedance is to be purely resistive, what load should be connected to terminals a-b of the circuits in Fig. 11.52 so that the maximum power is transferred to the load?

Find the rms value of the offset sine wave shown in Fig. 11.53.

Using Fig. 11.54, design a problem to help other students better understand how to find the rms value of a waveshape.

Determine the rms value of the waveform in Fig. 11.55.

Find the rms value of the signal shown in Fig. 11.56.

Find the effective value of the voltage waveform in Fig. 11.57.

Calculate the rms value of the current waveform of Fig. 11.58.

Find the rms value of the voltage waveform of Fig. 11.59 as well as the average power absorbed by a resistor when the voltage is applied across the resistor.

Calculate the effective value of the current waveform in Fig. 11.60 and the average power delivered to a resistor when the current runs through the resistor.

Compute the rms value of the waveform depicted in Fig. 11.61.

Find the rms value of the signal shown in Fig. 11.62.

Obtain the rms value of the current waveform shown in Fig. 11.63.

Determine the rms value for the waveform in Fig. 11.64.

Find the effective value of f(t) defined in Fig. 11.65.

One cycle of a periodic voltage waveform is depicted in Fig. 11.66. Find the effective value of the voltage. Note that the cycle starts at and ends at t 0 t 6 s.

Calculate the rms value for each of the following functions: (a) (b) (c) (d)

Design a problem to help other students better understand how to determine the rms value of the sum of multiple currents.

For the power system in Fig. 11.67, find: (a) the average power, (b) the reactive power, (c) the power factor. Note that 220 V is an rms value.

An ac motor with impedance is supplied by a 220-V, 60-Hz source. (a) Find pf, P, and Q. (b) Determine the capacitor required to be connected in parallel with the motor so that the power factor is corrected to unity.

Design a problem to help other students better understand apparent power and power factor.

Obtain the power factor for each of the circuits in Fig. 11.68. Specify each power factor as leading or lagging.

A 110-V rms, 60-Hz source is applied to a load impedance Z. The apparent power entering the load is 120 VA at a power factor of 0.707 lagging. (a) Calculate the complex power. (b) Find the rms current supplied to the load. (c) Determine Z. (d) Assuming that find the values of R and L. Z

Design a problem to help other students understand complex power

Find the complex power delivered by to the network in Fig. 11.69. Let vs 100 cos 2000t V.

The voltage across a load and the current through it are given by Find: (a) the rms values of the voltage and of the current (b) the average power dissipated in the load

For the following voltage and current phasors, calculate the complex power, apparent power, real power, and reactive power. Specify whether the pf is leading or lagging. (a) (b) (c) (d)

For each of the following cases, find the complex power, the average power, and the reactive power: (a) (b) (c) (d)

Determine the complex power for the following cases: (a) (b) (c) (d) 0Z0 40  (inductive) Vrms 220 V, P 1 kW, S 600 VA, Q 450 VAR (inductive) Q 2000 VAR, pf 0.9 (leading) P 269 W, Q 150 VAR (capacitive) I 10l6

Find the complex power for the following cases: (a) (b) (c) (d)

Obtain the overall impedance for the following cases: (a) (b) (c)

For the entire circuit in Fig. 11.70, calculate: (a) the power factor (b) the average power delivered by the source (c) the reactive power (d) the apparent power (e) the complex power

In the circuit of Fig. 11.71, device A receives 2 kW at 0.8 pf lagging, device B receives 3 kVA at 0.4 pf leading, while device C is inductive and consumes 1 kW and receives 500 VAR. (a) Determine the power factor of the entire system. (b) Find I given that Vs 120l45 V rms.

In the circuit of Fig. 11.72, load A receives 4 kVA at 0.8 pf leading. Load B receives 2.4 kVA at 0.6 pf lagging. Box C is an inductive load that consumes 1 kW and receives 500 VAR. (a) Determine I. (b) Calculate the power factor of the combination.

For the network in Fig. 11.73, find the complex power absorbed by each element.

Using Fig. 11.74, design a problem to help other students better understand the conservation of AC power.

Obtain the complex power delivered by the source in the circuit of Fig. 11.75.

For the circuit in Fig. 11.76, find the average, reactive, and complex power delivered by the dependent current source.

Obtain the complex power delivered to the resistor in Fig. 11.77 below.

Calculate the reactive power in the inductor and capacitor in the circuit of Fig. 11.78.

For the circuit in Fig. 11.79, find and the input power factor.

Given the circuit in Fig. 11.80, find and the overall complex power supplied.

For the circuit in Fig. 11.81, find .

Find in the circuit of Fig. 11.82.

Determine in the circuit of Fig. 11.83, if the voltage source supplies 2.5 kW and 0.4 kVAR (leading).

In the op amp circuit of Fig. 11.84, Find the average power delivered to the resistor.

Obtain the average power absorbed by the resistor in the op amp circuit in Fig. 11.85. 6-k

For the op amp circuit in Fig. 11.86, calculate: (a) the complex power delivered by the voltage source (b) the average power dissipated in the resistor

Compute the complex power supplied by the current source in the series RLC circuit in Fig. 11.87.

Refer to the circuit shown in Fig. 11.88. (a) What is the power factor? (b) What is the average power dissipated? (c) What is the value of the capacitance that will give a unity power factor when connected to the load?

Design a problem to help other students better understand power factor correction.

Three loads are connected in parallel to a source. Load 1 absorbs 60 kVAR at lagging, load 2 absorbs 90 kW and 50 kVAR leading, and load 3 absorbs 100 kW at (a) Find the equivalent impedance. (b) Calculate the power factor of the parallel combination. (c) Determine the current supplied by the source.

Two loads connected in parallel draw a total of 2.4 kW at 0.8 pf lagging from a 120-V rms, 60-Hz line. One load absorbs 1.5 kW at a 0.707 pf lagging. Determine: (a) the pf of the second load, (b) the parallel element required to correct the pf to 0.9 lagging for the two loads.

A 240-V rms 60-Hz supply serves a load that is 10 kW (resistive), 15 kVAR (capacitive), and 22 kVAR (inductive). Find: (a) the apparent power (b) the current drawn from the supply (c) the kVAR rating and capacitance required to improve the power factor to 0.96 lagging (d) the current drawn from the supply under the new power-factor conditions

A 120-V rms 60-Hz source supplies two loads connected in parallel, as shown in Fig. 11.89. (a) Find the power factor of the parallel combination. (b) Calculate the value of the capacitance connected in parallel that will raise the power factor to unity

Consider the power system shown in Fig. 11.90. Calculate: (a) the total complex power (b) the power factor

Obtain the wattmeter reading of the circuit in Fig. 11.91.

What is the reading of the wattmeter in the network of Fig. 11.92?

Find the wattmeter reading of the circuit shown in Fig. 11.93.

Determine the wattmeter reading of the circuit in Fig. 11.94.

The circuit of Fig. 11.95 portrays a wattmeter connected into an ac network. (a) Find the load current. (b) Calculate the wattmeter reading.

Design a problem to help other students better understand how to correct power factor to values other than unity

A 240-V rms 60-Hz source supplies a parallel combination of a 5-kW heater and a 30-kVA induction motor whose power factor is 0.82. Determine: (a) the system apparent power (b) the system reactive power (c) the kVA rating of a capacitor required to adjust the system power factor to 0.9 lagging (d) the value of the capacitor required

Oscilloscope measurements indicate that the peak voltage across a load and the peak current through it are, respectively, and . Determine: (a) the real power (b) the apparent power (c) the reactive power (d) the power factor

A consumer has an annual consumption of 1200 MWh with a maximum demand of 2.4 MVA. The maximum demand charge is $30 per kVA per annum, and the energy charge per kWh is 4 cents. (a) Determine the annual cost of energy. (b) Calculate the charge per kWh with a flat-rate tariff if the revenue to the utility company is to remain the same as for the two-part tariff.

A regular household system of a single-phase threewire circuit allows the operation of both 120-V and 240-V, 60-Hz appliances. The household circuit is modeled as shown in Fig. 11.96. Calculate: (a) the currents and (b) the total complex power supplied (c) the overall power factor of the circuit

A transmitter delivers maximum power to an antenna when the antenna is adjusted to represent a load of resistance in series with an inductance of If the transmitter operates at 4.12 MHz, find its internal impedance.

In a TV transmitter, a series circuit has an impedance of and a total current of 50 mA. If the voltage across the resistor is 80 V, what is the power factor of the circuit?

A certain electronic circuit is connected to a 110-V ac line. The root-mean-square value of the current drawn is 2 A, with a phase angle of (a) Find the true power drawn by the circuit. (b) Calculate the apparent power

An industrial heater has a nameplate that reads: 210 V 60 Hz 12 kVA 0.78 pf lagging Determine: (a) the apparent and the complex power (b) the impedance of the heater

A 2000-kW turbine-generator of 0.85 power factor operates at the rated load. An additional load of 300 kW at 0.8 power factor is added.What kVAR of capacitors is required to operate the turbinegenerator but keep it from being overloaded?

The nameplate of an electric motor has the following information: Line voltage: 220 V rms Line current: 15 A rms Line frequency: 60 Hz Power: 2700 W Determine the power factor (lagging) of the motor. Find the value of the capacitance C that must be connected across the motor to raise the pf to unity.

As shown in Fig. 11.97, a 550-V feeder line supplies an industrial plant consisting of a motor drawing 60 kW at 0.75 pf (inductive), a capacitor with a rating of 20 kVAR, and lighting drawing 20 kW. (a) Calculate the total reactive power and apparent power absorbed by the plant. (b) Determine the overall pf. (c) Find the current in the feeder line.

A factory has the following four major loads: A motor rated at 5 hp, 0.8 pf lagging ( ). A heater rated at 1.2 kW, 1.0 pf. Ten 120-W lightbulbs. A synchronous motor rated at 1.6 kVAR, 0.6 pf leading. (a) Calculate the total real and reactive power. (b) Find the overall power factor.

A 1-MVA substation operates at full load at 0.7 power factor. It is desired to improve the power factor to 0.95 by installing capacitors. Assume that new substation and distribution facilities cost $120 per kVA installed, and capacitors cost $30 per kVA installed. (a) Calculate the cost of capacitors needed. (b) Find the savings in substation capacity released. (c) Are capacitors economical for releasing the amount of substation capacity?

A coupling capacitor is used to block dc current from an amplifier as shown in Fig. 11.98(a). The amplifier and the capacitor act as the source, while the speaker is the load as in Fig. 11.98(b). (a) At what frequency is maximum power transferred to the speaker? (b) If how much power is delivered to the speaker at that frequency?

A power amplifier has an output impedance of It produces a no-load output voltage of 146 V at 300 Hz. (a) Determine the impedance of the load that achieves maximum power transfer. (b) Calculate the load power under this matching condition.

A power transmission system is modeled as shown in Fig. 11.99. If find the average power absorbed by the load.