3272-3 elec (3.9)

The power factor of an AC circuit is the. cosine of the phase angle. tangent of the phase angle. sine of the phase angle.

The Form Factor of an AC waveform can be found by. RMS value divided by the average value. average value divided by the RMS value. average value times the RMS value.

A differentiator has a time constant which is. long. equal to the input pulse. short.

If the frequency is increased in an AC circuit of pure resistance, the effect is. nothing. decreased resistance. increased resistance.

If an AC sine wave has an RMS value of 5V its peak value is. 6.37 V. 7.07 V. 14.14 V.

Apparent power in an AC circuit is found by. V * I * cosØ. V * I * sinØ. V * I.

A sine wave has a periodic time of 0.5 milliseconds, what is its frequency?. 200 Hz. 2Khz. 20Khz.

Phase angle is. the cosine of the peak value of an ac voltage. the difference in degrees of rotation between 2 alternating voltages or currents or a voltage and a current. the difference in degrees between the positive and negative parts of an AC sine wave.

The impedance of an AC circuit is measured in. ohms. kilovolt-amperes. amperes.

What happens to the current in a series resistive resonant circuit?. It is maximum. It is minimum. It is zero.

A circuit has 115 V RMS, 2.5A at 60 degrees, what is the power dissipated?. 79 W. 300 VA. 143 W.

In a resonant parallel circuit, current is. zero. minimum. maximum.

Power factor is. sin theta. tan theta. cos theta.

Peak factor in a standard AC circuit is. 1.11 times max. value of applied voltage. 1.414 times max. value of applied voltage. 0.707 time max. value of applied voltage.

The controlling wave in a CRT is. square. sawtooth. sinusoidal.

A wave form having equal amplitude and time base is a. rectangular. sawtooth. square waveform.

The Sine wave signals of a circular time base are. in phase. phase separated by 90°. phase separated by 180°.

A differentiator has a time constant that will give. a long pulse. a short pulse. a continuous output.

What is the power factor in a purely resistive circuit?. Equal to 1. Less than 1 but greater than zero. Greater than 1.

In an A.C circuit, what happens if frequency is reduced?. Inductive elements may be damaged. Capacitive elements may be damaged. There will be no effect.

What is the relationship between the voltage and the current in an A.C circuit containing resistance and inductance?. Current lags voltage by 90°. Current lags voltage by up to 90°. Current leads voltage by up to 90°.

Power factor relates to. horsepower and Watts. KW and KVAR. true power and apparent power.

If current lags voltage by 90°, the circuit is. resistive. capacitive. inductive.

A low frequency supply. will make the circuit operate faster due to the reduced impedance. may damage inductive components. will have no effect on inductive components.

In a parallel R, L, C circuit, the value of the capacitor is quadrupled, then the value of the impedance would. remain the same. reduce. increased.

In a capacitive circuit, if the frequency is increased. reactance remains the same. impedance increases. the current increases.

In a tuned circuit at resonance, the circuit will be. resistive. capacitive. inductive.

A circuit has a resistance of 50 ohms and an inductance of 0.2 Henry. If it is connected to a 200 volt 50 Hz supply the reactance will be. 6.284 ohms. 62.84 ohms. 31.42 ohms.

At resonant frequency the phase difference between the voltage and current of an AC supply feeding an inductive and capacitive network is. 90 degrees. 0 degrees. 180 degrees.

An increase in which of the following factors will cause an increase in the inductive reactance of a circuit?. Inductance and frequency. Resistance and capacitive reactance. Resistance and voltage.

When a circuit with a series inductance and capacitance is at resonant frequency. the current in the circuit decreases. the impedance of the circuit is such that the voltage is in phase with the current. the impedance of the circuit is such that the voltage leads the current by exactly 90 degrees.

A pure capacitor, inductor and resistor are connected in series and the voltage drops across each are 10V and the total current flowing in the circuit is 1A. How much true power is the circuit consuming?. 30VA. 30W. 10W.

If a capacitor 1µF and an inductor 10mH are connected in parallel what is their approximate resonant frequency?. 1.6 kHz. 62 Hz. 3.2 MHz.

Current in an inductive circuit will. lag voltage. lead voltage. be at unity.

The impedance of a series tuned circuit at resonance is. zero. minimum. maximum.

In an inductive resistive circuit, 1 amp flows from a supply of 100V dissipating 50 Watts of power. The phase angle is. 60°. 90°. 45°.

In a series LCR circuit at resonance, R = 100 ohms, L and C are each 10 ohms. The total impedance is. zero ohms. 100 ohms. 30 ohms.

In a high Q parallel resonant circuit, what happens to impedance if capacitance is increased by a factor of 4?. It increases by factor of 4. It reduces by 75%. It remains the same.

A parallel circuit at resonance has its impedance at a. maximum. zero. minimum.

The formula for impedance in a series circuit is the root of. R2 + (XC-XL)2. R2 -(XL-XC)2. R2 + (XL-XC)2.

In a parallel LCR circuit, if the capacitance is increased by 4 times, what happens to the impedance of the capacitor?. Increases by 4 times. Remains the same. Decreases by 75%.

If the frequency to a capacitor increases, the current through it. decreases. increases. is zero.

If in a electrical circuit there is a difference between the capacitive reactance and the inductive reactance, what would the power factor of the circuit be?. More than unity. Less than unity. Unity.

In a Series LC circuit if the value of the capacitance is increased then the power factor will be. greater than 1. less than 1. equal to 1.

What is the current in the circuit with a resistance of 8 ohms, inductive reactance of 12 ohms, capacitive reactance of 18 ohms with 20 volts applied across it?. 10 amps. 1 amp. 2 amps.

A circuit containing a resistor, capacitor and inductor where resonant frequency is met, what will the impedance of the circuit be?. Maximum. Resistance across the resistor. Zero.

How many turns does the secondary winding of a 2:1 step-up transformer have?. Less than primary. More than primary. Less turns but with thicker wire.

To reduce eddy currents in a transformer you would. increase the thickness of laminations in the magnetic core. reduce the number of turns on the primary winding. reduce the thickness of laminations in the magnetic core.

A transformer has an input of 400V and a ratio of 2:1. If the transformer is delta / star wound, what will the line voltage output be?. 115V. 346V. 200V.

A Transformer with 115V primary voltage and a ratio of 5:1 is supplying a landing light (load 24V 45 amps) is used, what is the current drawn?. 205 amps. 5 amps. 9 amps.

A Transformer has 4500 secondary turns and 750 primary turns. Its turns ratio is. 6:1. 1/6. 1:6.

The point of coercivity occurs when the. magnetic flux is zero even though a magnetizing force is being applied. magnetizing force reaches a peak positive or negative value. magnetizing force applied causes the material to become magnetically saturated.

The primary winding of a 3-phase transformer. is delta wound. could be either delta or star wound. is star wound.

In a transformer, if the rate of change of current increases, the mutual inductance will. decrease. remain the same. increase.

A 4:1 step down transformer draws 115 V and 1 A. The output power will be. 28.5 V at 16 A. 460 V at 0.25 A. 28.5 V at 4 A.

The secondary coil of a transformer has 1500 turns and 10Ohm resistance. The primary coil has 1kOhm resistance. How many turns does the primary coil have?. 15,000. 1,500,000. 150,000.

In a star wound primary transformer, how could you wind the secondary winding?. Star only. Either delta or star. Delta only.

A step up transformer has. two windings. one winding. three windings.

In a transformer core loss is 200 W and copper loss is 220W at no load. What is the core loss at full load?. 200 W. 0 W. 220 W.

The secondary winding of a transformer has an impedance of 10 ohms and 1500 turns. For the primary winding to have an impedance of 1 kilohm, how many turns must it have?. 15,000. 1,500,000. 150,000.

Eddy currents in a transformer core are reduced by. decreasing the thickness of the laminates. making the core from a solid block. increasing the thickness of the laminates.