BASIC ELECTRICITY Flashcards
The working voltage of a capacitor in an ac circuit should be
at least 50 percent greater than the highest applied voltage
The term that describes the combined resistive forces in an ac circuit is
impedance
The basis for transformer operation in the use of alternating current is mutual
inductance
The opposition offered by a coil to the flow of alternating current is called (disregard resistance)
inductive reactance
An increase in which of the following factors will cause an increase in the inductive reactance of a
circuit?
inductance and frequency
When different rated capacitors are connected in series in a circuit, the total capacitance is
less than the capacitance of the lowest rated capacitor
Capacitors are sometimes used in dc circuits to
smooth out slight pulsations in current/voltage
In an ac circuit, the effective voltage is
Less than the maximum instantaneous voltage
The amount of electricity a capacitor can store is directly proportional to the
plate area and inversely proportional to the distance between the plates
Unless otherwise specified, any values given for current or voltage in an ac circuit are assumed to be
effective values
When different rated capacitors are connected in parallel in a circuit, the total capacitance is
(Note: C(T) = C(1) + C(2) + C(3) . . .)
equal to the sum of all the capacitances
When inductors are connected in series in a circuit, the total inductance is (where the magnetic fields of
each inductor do not affect the others)
(Note: L(T) = L(1) + L(2) + L(3) . . .)
equal to the sum of the individual inductance
The potential difference between two conductors which are insulated from each other is measured in
volts
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?
24 volts
When calculating power in a reactive or inductive ac circuit, the true power is
less than the apparent power
The correct way to connect a test voltmeter in a circuit is
in parallel with the unit
Which term means .001 ampere?
milliampere
.002KV equals
2.0 volts
What unit is used to express electrical power?
watt
Which statement is correct when made in reference to a parallel circuit?
the total current is equal to the sum of the currents through the individual branches of the circuit
Which of the following are commonly used as rectifiers in electrical circuits?
1. Anodes.
2. Cathodes.
3. Diodes
3
Diodes are used in electrical power supply circuits primarily as
rectifiers
Transfer of electric energy from one circuit to another without the aid of electrical connections
is called induction
Which is correct in reference to electrical resistance?
if one of three bulbs in a parallel lighting circuit is removed, the total resistance of the circuit will become greater
What happens to the current in a voltage step-up transformer with a ratio of 1 to 4?
the current is stepped down by a 1 to 4 ratio
Which of these will cause the resistance of a conductor to decrease?
decrease the length or increase the cross sectional area
Through which material will magnetic lines of force pass the most readily?
iron
Which is correct concerning a parallel circuit?
total resistance will be smaller than the smallest resistor
The voltage drop in a circuit of known resistance is dependent on
the amperage of the circuit
A thermal switch, or thermal protector, as used in an electric motor, is designed to
open the circuit in order to allow cooling of the motor
When referring to an electrical circuit diagram, what point is considered to be at zero voltage?
the ground reference
What is the purpose of the ground symbol used in electrical circuit diagrams?
to show that there is a return path for the current between the source of electrical energy and the load
In a P-N-P transistor application, the solid state device is turned on when the
base is negative with respect to the emitter
In an N-P-N transistor application, the solid state device is turned on when the
base is positive with respect to the emitter
Typical application for zener diodes is as
voltage regulators
Forward biasing of a solid state device will cause the device to
conduct
If electrolyte from a lead-acid battery is spilled in the battery compartment, which procedure should be
followed?
apply sodium bicarbonate solution to the affected area followed by a water rinse
Which statement regarding the hydrometer reading of a lead-acid storage battery electrolyte is true?
the hydrometer reading does not required a temperature correction if the electrolyte temperature is 80 degrees F
A fully charged lead-acid battery will not freeze until extremely low temperatures are reached because
most of the acid is in the solution
What determines the amount of current which will flow through a battery while it is being charged by a constant voltage source?
the state- of –charge of the battery
Which of the following statements is/are generally true regarding the charging of several aircraft batteries together?
1. Batteries of different voltages (but similar capacities) can be connected in series with each other across the charger, and charged using the constant current method.
2. Batteries of different ampere-hour capacity and same voltage can be connected in parallel with each other across the charger, and charged using the constant voltage method.
3. Batteries of the same voltage and same ampere-hour capacity must be connected in series with each other across the charger, and charged using the constant current method.
1 and 2
The method used to rapidly charge a nickel-cadmium battery utilizes
constant voltage and varying current
The purpose of providing a space underneath the plates in a lead acid battery’s cell container is to
prevent sediment buildup from contacting the plates and causing a short circuit
Which condition is an indication of improperly torqued cell link connections of a nickel-cadmium battery?
heat or burn marks on the hardware
The presence of any small amount of potassium carbonate deposits on the top of nickel-cadmium battery cells in service is an indication of
normal operation
What is the likely result of servicing and charging nickel-cadmium and lead acid batteries together in the same service area?
contamination of both types of batteries
The electrolyte of a nickel-cadmium battery is the lowest when the battery is
in a discharge condition
The electrolyte of a nickel cadmium battery is highest when the battery is
in a fully charge condition
The end-of-charge voltage of a 19-cell nickel-cadmium battery, measured while still on charge,
depends upon its temperature and the method used for charging
Nickel-cadmium batteries which are stored for a long period of time will show a low liquid level because
electrolyte becomes absorbed into the plates
How can the state-of-charge of a nickel-cadmium battery be determined?
by a measured discharged
What may result if water is added to a nickel-cadmium battery when it is not fully charged?
excessive spewing is likely to occur during the charging cycle
In nickel-cadmium batteries, a rise in cell temperature
causes a decrease in internal resistance
Which of the following best describes the contributing factors to thermal runaway in a nickel-cadmium battery installed in an aircraft?
low internal resistance intensifies by high cell temperature and a high current discharge/charge rate in a constant potential charging system
When a charging current is applied to a nickel cadmium battery, the cells emit gas
toward the end of the charging cycle
