600 - Practice Final Exam

Which of the following statements is correct about polarized electrolytic capacitors?

• They must be installed in a heat sink

• Voltage polarity must be correct

• The dielectric is usually mica

• The plates are nonmetallic

What is the time constant for a circuit with 150K ohms and 2 microfarad capacitor?

• 1 second

• .3 seconds

• 5 seconds

• 15 seconds

What happens in a circuit, when the capacitor voltage equals the source voltage?

• Current flow increases in the circuit

• Voltage increases in the circuit

• Resistance decreases in the circuit

• Current flow stops in the circuit

In a DC circuit, which is correct about capacitors the instant power is applied?

• Current is maximum

• Voltage is maximum

• Resistance is maximum

• Capacitance is minimum

If a circuit has a capacitor of 5 microfarads and a source voltage of 120 Volts DC through a resistance of 200K, how long will it take to fully charge?

• 20 seconds

• 5 seconds

• 2 seconds

• 1 second

What is the unit of inductance?

• Henry

• Watt

• Farad

• Coulombs

Which of the following statements describes how an air coil is magnetized?

• As current is increased, it eventually reaches saturation.

• As current is increased, the field will always expand.

• As current is decreased, the field expands outward.

• As current is decreased, it eventually reaches saturation.

Which term describes a material's ability to pass magnetic lines of force?

• Capacitance

• Permeability

• Hysteresis

• Dielectric constant

What effect does counter electromotive force (CEMF) have in a inductive circuit?

• It is the force of the applied voltage to cause a magnetic field to form.

• It is the force which is applied to an armature windings to start it turning.

• It is an opposing force to the applied voltage which resists changes in circuit current.

• It is an aiding force to the applied voltage to increase circuit current.

At what point is counter electromotive (CEMF) greatest in an inductive circuit?

• When current reaches maximum

• When the rate of change for current is maximum

• When the current reaches minimum

• When the rate of change for current is minimum