3. Electrical fundamentals - Q&A

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.

In the circuit shown, the power developed across the 10 kilo ohm resistor is

• 250 mW.
• 250 W.
• 50 mW.

If there was a mainly inductive load on an AC generator, the voltage with respect to the current would

• lag.
• be in phase.
• lead.

Two 12V 40 amp hour batteries connected in parallel will produce

• 24V 80 ah.
• 12V 80 ah.
• 24V 40 ah.

A single phase circuit has an input voltage of 100V. The current is 10A and the circuit has a power factor of 0.5. The true power is

• 50W.
• 1000W.
• 500W.

A circuit has 115 V RMS, 2.5A at 60 degrees, what is the power dissipated?

• 79 W.
• 300 VA.
• 143 W.

The series wound generator`s terminal voltage will, when below saturation

• increase with an increase in load.
• decrease with an increase in load.
• decrease with a decrease in rotational speed.

An inductor has 1,000 turns of wire and a cross sectional area of 0.001m2. If the core has a permeability of 0.000,001 and the coil is 0.1m. What is the value of the inductor?

• 100microH.
• 100mH.
• 10mH.

The dots on the transformer symbol shown are called, and indicate

• phasing dots, point that have the opposite polarity at the same moment in time.
• phasing dots, point that have the same polarity at the same moment in time.
• quadrature dots, points are 90o out of phase.

If an AC sine wave has an RMS value of 5V its peak value is

• 6.37 V.
• 7.07 V.
• 14.14 V.

If the phase voltage in a star connected generator is 200V what will be the line voltage?

• 115V.
• 346V.
• 200V.

In a 4:1 step-up transformer, 120V is applied to the primary, and the load on the secondary is 1600 Ohms. What is the current in the primary?

• 0.075A
• 1.2A
• 3A

A 4:1 step down transformer draws 115 V and 1 A. The output power will be

• 460 V at 0.25 A.
• 28.5 V at 16 A.
• 28.5 V at 4 A.

What polarity do interpoles take in a DC generator?

• The same as the next main pole behind in the direction of rotation.
• Either, providing they lay on M.N.A.
• The same as the next main pole ahead in the direction of rotation.

A 24-volt source is required to furnish 48 watts to a parallel circuit consisting of four resistors of equal value. What is the voltage drop across each resistor?

• 12 volts.
• 24 volts.
• 3 volts.

A starter generator has a

• low resistance series field and a low resistance shunt field.
• low resistance series field and a high resistance shunt field.
• high resistance series field and a low resistance shunt field.

What is the current through resistor C?

• 4.5A
• 18A
• 9A

Reactive sparking is reduced by

• interpoles.
• compensating windings.
• auxiliary windings.

In the circuit shown, impedance will be

• 5 ohms.
• 9 ohms.
• 7 ohms.

The diagram shows a 200V long shunt generator. What is the voltage across the series resistor?

• 10V
• 6V
• 30V

If you apply this waveform to this circuit, what is the output across the capacitor?

• Pulsed negative
• Pulsed positive
• Zero

Formation of white crystals of potassium carbonate on a properly serviced Ni-cd battery indicates

• over charged.
• full charged.
• under charged.

A shunt is used with

• an ammeter.
• a voltmeter.
• an ohmmeter.

What is the value of a monolithic capacitor with 103 on it?

• 1000pf.
• 10,000pf.
• 100,000pf.

A conductor with a positive Q (charge) of 4C has 12.56 x 1018 electrons added to it. It will have a Q =

• 6.
• 2.
• 0.