CDC 3E051A Vol.1 Unit 1

What two different ways can scientists can combine elements?

A) Atoms or molecules.
B) Compounds or mixtures.
C) Atoms or compounds.
D) Molecules or mixtures.

In which shell of an atom are the valence electrons located?

A) The first.
B) The second.
C) The outermost.
D) The middle.

How would you best describes a positive ion?

A) An atom that lost an electron and has more protons.
B) An atom that cannot throw off any protons.
C) An atom that lost a proton and has more electrons.
D) An atom that has an equal number of electrons and protons.

What material permits a large number of free electrons to move through it?

A) Conductor.
B) Resistor.
C) Ion.
D) Insulator.

Which smallest current can be fatal under certain conditions?

A) One-third of 1 amp.
B) One-tenth of 1 amp.
C) One-half of 1 amp.
D) One-eighth of 1 amp.

What is used to move a sufficient number of electrons to perform a useful job?

A) Voltage.
B) Current.
C) Inductance.
D) Heat.

How is resistance defined with respect to electricity?

A) The potential difference offered by a material.
B) The opposition to voltage in an electrical circuit.
C) The movement of electrons through a conductor.
D) The opposition to current flow.

According to Ohm's law, how much voltage is needed to push one ampere of current through one ohm of resistance?

A) 10 volts.
B) 0.1 volt.
C) 1 volt.
D) 100 volts.

What factor normally causes the resistance of a conductor to increase?

A) Increase in temperature.
B) Increase in size.
C) Decrease in temperature.
D) Decrease in length.

What unit of measurement is used to measure electrical power?

A) Ohms.
B) Volts.
C) Amps.
D) Watts.

How much power does a 3-horsepower motor consume?

A) 0.755 kilowatts (kW).
B) 2.238 kW.
C) 2.023 kW.
D) 1.534 kW.

When do the magnetic lines of force in a magnet cross?

A) Magnetic lines of force never cross each other.
B) When the south pole of a magnet is placed near the north pole of another magnet.
C) When a permanent magnet and a temporary magnet are put together.
D) When the north pole of a magnet is placed near the north pole of another magnet.

How can a polarity be created and the strength of the magnetic lines of force around a conductor be increased?

A) By looping coils close together.
B) By increasing the size of the conductor.
C) By increasing resistance.
D) By decreasing current.

What methods are the two most common for producing voltage?

A) Magnetic and mechanical.
B) Magnetic and heat.
C) Chemical and heat.
D) Chemical and mechanical.

What three things are needed to produce voltage by the principle of electromagnetic induction?

A) Coil, core, and current.
B) Coil, conductors, and relative motion.
C) Magnet, housing, and prime mover.
D) Magnetic field, a conductor, and relative motion.

What type of current flow is the result of voltages produced by batteries and thermocouples?

A) Easily transformed current.
B) Alternating current (AC)
C) Current of no commercial value.
D) Direct current (DC)

What type of current flow cannot be transformed from a higher voltage to a lower voltage?

A) Low current.
B) Alternating current (AC)
C) Direct current (DC)
D) Electric.

Which formula is the correct one for finding the resistance of a circuit?

A) Voltage divided by current.
B) Voltage divided by resistance.
C) Current divided by resistance.
D) Current divided by voltage.

How much resistance of a circuit is applied with voltage of 120 volts and a current flow of 9 amperes?

A) 108 ohms.
B) 1.3 ohms.
C) 0.13 ohms.
D) 13.33 ohms.

How much current flow is in a circuit with 24 volts applied and with 72-ohms resistance?

A) 0.728 amperes.
B) 33.0 amperes
C) 0.33 amperes.
D) 3.3 amperes.

What ohm measurement is the total resistance of a 5-ohm resistor and a 20-ohm resistor in parallel?

A) 2.5 ohms.
B) 2 ohms.
C) 4 ohms.
D) 5.5 ohms.

What ohm measurement is the total resistance of a 4-ohm resistor, a 10-ohm resistor, and a 12-ohm resistor in parallel?

A) 3.9 ohms.
B) 2.3 ohms.
C) 4.2 ohms.
D) 3.2 ohms.

What measurement is the current flow in amperes of a circuit with an applied voltage of 120 volts and a power consumption of 600 watts?

A) 0.5 amperes.
B) 5 amperes.
C) 2.5 amperes.
D) 2 amperes.

What amount of power in watts is consumed by a circuit with 120 volts applied and a resistance of 12 ohms?

A) 1200 watts.
B) 1440 watts.
C) 12 watts.
D) 10 watts.

How many watts of power are present in a 5-ohm unit of resistance in which 2 amperes are flowing?

A) 10 watts.
B) 15 watts.
C) 20 watts.
D) 2.5 watts.

What completes an electrical cycle of an alternating current (AC) generator?

A) One positive and one negative alternation.
B) One negative alternation.
C) One positive alternation.
D) One positive and two negative alternations in one second.

How many rotations per minute (rpm) must a two-pole generator rotate to produce 60 hertz?

A) 1,200 rmp.
B) 3,600 rmp.
C) 4,000 rmp.
D) 1,800 rmp.

How is the measurement of the apparent power of an alternating current (AC) electrical system expressed?

A) Volt-amperes.
B) Millivolt-amperes.
C) Kilovolt-amperes.
D) Picovolt-amperes.

What is the capacitance of a 125 microfarads (uF) capacitors when converted to farads?

A) 0.125 F.
B) .000125 F.
C) .00125 F.
D) .0125 F.

The rules and equations for direct current (DC) circuits apply to alternating current (AC) circuits having

A) Reactive load elements alone.
B) Capacitive load elements alone.
C) Resistive and reactive load elements.
D) Resistive load elements alone.

A 110-volt alternating current (AC) motor records 20 in-line amperes and the in-line wattmeter shows only  1,936 watts being consumed. What would be the power factor of the AC circuit?

A) 80 percent power factor (pf).
B) 86 percent power factor (pf).
C) 88 percent power factor (pf).
D) 83 percent power factor (pf).

What is the purpose of an electrical generator?

A) Converts electrical energy to mechanical energy.
B) Converts kinetic energy to potential energy.
C) Converts kinetic energy to electrical energy.
D) Converts mechanical energy to electrical energy.

What type of generator has brushes riding on the commutator to carry the current to an external circuit?

A) Potential type.
B) Universal.
C) Alternating current type.
D) Direct current type.

What features is the advantage of having a rotating magnetic field alternator?

A) Output is taken from the stationary stator coils.
B) It requires less power to rotate the magnetic field.
C) Output is taken from the commutator.
D) It requires no slip rings and brushes.

The voltage of a primary cell depends on the type of

A) electrode material and type of cell.
B) cell and type of terminal posts.
C) electrolyte and the electrode material.
D) electrolyte and type of cell.

Even though the open-circuit voltage of a lead-acid storage battery is approximately 2.2 volts, what number is the normal rating?

A) 2.5.
B) 2.9.
C) 2.7.
D) 2.0.

A step-up transformer produces a secondary voltage

A) higher and secondary current lower than the voltage and current in the primary.
B) and current higher than the voltage and current in the primary.
C) lower and secondary current higher than the voltage and current in the primary.
D) and current lower than the voltage and current in the primary.