AC Circuits Questions and Answers

A 120 V ac voltage source is connected across a 2 0 micro F capacitor What will be current to the capacitor if the frequency of the source is 60 Hz 50 mA 70 mA 90 mA

A coil with an inductance 0 14 H and a resistance of 12 ohm is connected across a 110 V 25 Hz source Compute the current in the coil and the phase angle between the current and supply voltage O 2 2 A 22 O 71 mA 50 O 4 4 A 61 3 O 20 mA 13

In the previous problem you tried to draw a circuit diagram for a series circuit containing a R 100 ohm resistance a coil with L 0 1 H inductance and a C 20 F capacitor connected across a 110 V 60 Hz voltage source What would be the voltmeter readings across R L and C Show your work on scratch papers Show your work in calculating the resonance frequency of a circuit containing an inductance L 40 0 mH and a capacitance C 600 pF Edit View Insert Format Tools Table 12nt Paragraphy B T Ax a 7 T x

Draw a circuit diagram for a series circuit containing a R 100 ohm resistance a with L 0 1 H inductance and a C 20 micro F capacitor connected across a 11 Hz voltage source What will be the current 1 through the supply and the phase between current and the source Edit View Insert Format Tools Table

Y 120 V 1 09 A O 210 V 1 90 A Voltage An AC voltage source has an output of v 170 V sin 27ft and connected to a 110 S2 resistor as shown in the figure Therefore the approximate value for the rms voltage and rms current through the resistor would be O 120 V 1 55 A Current time O None of the choices mentioned here

Question 2 Should V and Vc be equal at resonance frequency explain why yes or no

www V to 1 sin at V V HH Ve A resistor R capacitor C and inductor L are connected in series across an AC generator vs Vm sin 27ft Which of the following statements is false O The rms voltage across the combination of the three elements equals the algebraic sum of the rms voltages across each element separately The instantaneous voltage across the inductor leads the current by 90 O The voltages across the resistor capacitor and inductor are not in phase O The instantaneous voltage across the capacitor lags the current by 90

mm 120 Volts v What type of signal does this graph show O External Digital O Neutral O Analog

AC Source Electrical Paathds O As ft both Xc and XL O As ft Xc and XLT As ft both Xc and XL Purely C Capacitive Load Fig Purely Capacitive Circuit You got two different circuits as shown Variation of each reactance with frequency is as below O As ft Xc T and XL Vs

Question 5 For the series RL circuit shown below determine 1 True power 2 44 A 440 V 60 Hz O 2 Inductive reactive power 3 Apparent power R 150 2 Z 18022 XL 100 2 366 V 244 V

An AC series RL circuit is made up of a resistor that has a resistance value of 1500 and an inductor that has an inductive reactance value of 100 Q Calculate the impedance and the phase angle theta 8 of the circuit

For the series RL circuit shown in Below 140 V 0 Hz R Z 180 22 150 X 100 ET ER 1 Calculate the value of the current flow 2 Calculate the value of the voltage drop across the resistor 3 Calculate the value of the voltage drop across the inductor 4 Calculate the circuit phase angle based on the voltage drops across th resistor and inductor 5 Express all voltages in polar notation 6 Use a calculator to convert all voltages to rectangular notation

In the following figure the reading of ideal AC voltmeter will be X 300 mmmm 400 www 190 X 300 HE 100

6 A circuit is constructed with a 1000 resistor a 1 00 x 10 F capacitor and a 2 00 H inductor This circuit is connected to a 100 Vmax generator The frequency of the generator can be varied What frequency will produce the lowest impedance What is the rms current in the circuit at this frequency

3 A 100 resistor 0 0250 H inductor and 40 x 10 F capacitor are connected in series to a 20 V rms AC source The frequency of the source can be varied What is the rms current in the circuit when the frequency is 200 Hz

3 For the following circuit determine the value of vo t 5 pts 27 k www 1 2290 mA 1020 V j10 kn b W 5 6 k

Quality factor of a series LCR circuit is 0 6 If definition of quality factor is changed such that now limiting frequency of bandwidth is taken uptord of maximum power rather than half of maximum power standard definition then what will be quality factor of given circuit 1

Problem 2 In Lecture a while ago we considered the problem of an AC circuit in which the generator capacitor resistor and inductor are all in parallel That is what is the total complex impedance Z of the L R C all in parallel And what is the complex current amplitude I and its magnitude I given the AC input voltage with amplitude V and frequency w Make a rough plot of current magnitude I as a function of frequency w for a fixed voltage amplitude V Mark the location and value of the minimum current amplitude if there is a minimum

A 10 0 Q resistor is hooked up in series with an 8 0 Q resistor followed by a 27 00 resistor The circuit is powered by a 9 0 V battery a Draw a labeled circuit diagram for the circuit described b Calculate the equivalent resistance c Calculate the voltage drop across each resistor in the circuit

In the circuit shown in the figure the inductance of coil is L 10 mH and capacitance of the capacitor is C 0 2 mF The circuit is powered by an A C voltage source If value of current measured by ammeter does not depend on resistor then frequency of source is R C O 160 Hz O 140 Hz O 180 Hz 200 Hz L 00000

1 For the following circuit the rms value sinusoidal voltage source is V its linear frequency f 30 and its phase 0 45 6 pts a V C ell www R a Find the values of C L R if Zc j3 Q2 Z1 j3 2 ZR 4 2 2 pts I b Find the value of Zeq 1 pts c Find the phasor voltage Va express it in terms of the peak voltage value and the phase angle in degrees 1 pts

A 1 0 F and a 2 0 F capacitor are connected in series across a 6 0 V voltage source a What is the charge on the 1 0 F capacitor b What is the voltage across the 2 0 F capacitor 1

Four capacitors are connected across a 90 V voltage source as shown in the figure 2 0 F 3 0 F 90 V 4 0 uF 6 0 F a What is the charge on the 4 0 uF capacitor b What is the charge on a 2 0 F capacitor c What is the charge on the 3 0 F capacitor d What is the potential difference across the 6 0 F capacitor

Problem 3 If you have an have does the total complex impedance Z approach as w LC 1 2 If you the same two elements in parallel what does the total complex impedance approach in this same limit Now imagine that associated with the inductor L there is a resistance R That is there is always a small resistance R in series with the inductor in both cases Now what do your two limits become Note To solve this problem you will have to use the fact that complex impedances add in series in parallel the way resistances do but in complex

In an RLC circuit a resistor R=25Ω, an inductor L=30mHand a capacitor C=12µF are connected in series with an AC source with Vrms=80V and f=500Hz i) Determine the total impedance. ii) Determine the rms current in the circuit. iii) Determine the phase angle. iv) Determine the rms value of the voltage across R, L, and C.

Find the Thevenin equivalent with respect to the terminals a,b for the circuit(Figure 1)if v = 300 V, i = 17 A.

A 45 W light bulb operates with an effective ac voltage of 110 V. (a) What is the effective current through the light bulb? (b) From Ohm's law, what is the resistance of the light bulb? Part Answer (a) (b)

A 1.00mH inductor and one 1.00μF capacitor are connected in series. The current in the circuit is described by I = 20t where t is in seconds and I is in amperes. Initially, the capacitor has no charge. Determine a. The voltage across the inductor as a function of time, b.The voltage across the capacitor as a function of time c.The time when the energy stored in the capacitor first exceeds that in the inductor.

011/12-13 O11 12 13 In the above circuit if R₁ R₂ R3, and the currents passing through the corresponding resistances are 1₁, 12, and 13. then, 11 12 13 V O111213 R₂₁

A 100Ω resistor, 2.00 mH inductor, and 50 µF capacitor are connected in series to an AC voltage source. If the maximum voltage is 75.0 V and the frequency is 500 Hz, what is the rms current in the circuit?

38. Magnets are involved in the production of electricity for many power generators. True False

A power station is located 120km from a town that requires 60MW of power. The transmission lines have a resistance of 0.100/km. Determine the output voltage of the transformer at the power station so that the overall efficiency is 98 %, assuming that the transformers are 100% efficient.

Find the charge on the capacitor in an LRC-series circuit at t = 0.04 s when L = 0.05 h, R = 3, C = 0.008 f, E(t) = 0 V, q(0) = 3 C, and i(0) = 0 A. (Round your answer to four decimal places.) Determine the first time at which the charge on the capacitor is equal to zero. (Round your answer to

A 65 Ω resistor, an 7.8 μF capacitor, and a 39 mH inductor are connected in series in an ac circuit. Calculate the impedance for a source frequency of 30.0 kHz.

An electric motor is being powered with a voltage amplitude of 350 V at 60 Hz. The motor draws a current amplitude of 13.0 A. Find the root-mean-square voltage.

Consider the power dissipated in a series R-L-C circuit with R=3600, L = 120mH, C=0.800μF, V = 50V, and w=11300rad/s. The current and the voltages in this circuit are not in phase with each other. Using the values given, the phase angle was found to be 74°, and the current amplitude I was found to be 3.9x10-2 A. Calculate the power factor and the average power to the entire circuit and to each circuit element. If the inductance L in this circuit could be changed, what value of L would give a power factor of unity?

When a resistance R is connected in series with an (non-resistive) element A, the electric current is found to lead the voltage by angle of 30°. When the same resistance is connected in series with (non-resistive) element B, current lags by 60°. When R, A, B are connected in series, the phase difference between current and voltage is tan-1(k/√3) Find the value of k.

An alternating current generator has an internal resistance Rg and an internal inductive reactance of magnitude Xg. It is used to supply power to a passive load consisting of a resistance R₁ (fixed) and a capacitive reactance of magnitude Xc. For maximum power to be delivered from the generator to the load the value of X, is equal to : Rg Xg Equal and opposite of reactance of generator. Equal in magnitude of impendence of generator.

If current amplitude is 5A and angular frequency of source is 100 rad/sec and resistance is 100 , inductance is 4 H and capacitance is 20 uF. The peak value of source voltage is 250 n Find n.

Quality factor of a series LCR circuit is 0.6. If definition of quality factor is changed such that now limiting frequency of bandwidth is taken upto 1/3rd of maximum power rather than half of maximum /power (standard definition), then what will be quality factor of given circuit ?

An alternating source of 200 V (RMS) is applied in series LCR circuit. At resonance potential difference across inductor and capacitor is 300 volts. Then potential difference across (RMS value) resistance is: 300 200√2 200 Zero

A voltage source V = 200√2 sin (wt+0) connected in series LCR circuit having resistance, inductance and capacitance as 100 2, 1H and 9 uf respectively. Then max power consumed will be 400 W 800 W 200 w 100 w

Choose the incorrect statement regarding transformers: In step-up transformers, the primary coil is made from thick wire so that it can sustain high current. Transformers do not work on DC voltage In transformers, EMF induced in secondary coil is 180° out of phase with EMF applied across primary coil. In transformers, steel is preferred over soft -iron as cores inside current carrying coils

A DC motor operates with 220 V mains. Initially it draws a current of 20 A. The resistance of starter is 6Ω. When the motor runs at its full speed it consumes 500 W power. Find the current drawn by it.

A step-up down transformer operated on a 2.5 kV line. It supplies a load with 20 A. the ratio of primary winding to the secondary winding is 10:1. If the transformer is 90% efficient, calculate i) the power output ii) The voltage end iii) The current in the secondary coil.

A star-connected, 3-phase, 4-pole, 50 Hz alternator has a single layer winding in 24 stator slots. There are 50 turns in each coil and the flux per pole is 0.05 Wb. Find the open-circuit voltage. (3715 V)