Flashcards in Jeppesen Oral- Chapter 3 (Basic Electricity) Deck (45)
One kilowatt is equal to how many watts?
What law describes the most fundamental or basic relationships in an electrical circuit?
What are the three elements in Ohm's law?
Voltage, current, resistance
How would you write ohms law as an equation?
E=IR R=E/I I=E/R
If the resistance in a DC circuit remains the same but the voltage doubles, what happens to the amount of current flowing in the circuit?
It also doubles
In DC circuits, what unit measures power?
What three elements are required to form an electrical circuit?
Source of power (EMF), consumer (load), Conductors to connect the two
DC circuits can take on of three forms or types. What are they?
Series, parallel, complex
A 24 volt lead-acid battery has how many cells?
A fully charge lead-acid battery has a Specific gravity that varies between what two values?
1.275 and 1.3
You must apply a correction to the Specific gravity reading of the electrolyte of a lead-acid battery when the temperature is outside what two values?
less than 70F and more than 90F
What is the reason for having separate facilities for storing and servicing nickel-cadmium and lead-acid batteries?
To prevent cross contamination since the two electrolytes are chemically oposite
The state of charge of a nickel-cadmium battery cannot be determined by measuring the specific gravity of the electrolyte for what reason?
No real change of SPG when being charged or discharged
What is the principal advantage of AC current over DC current?
Power can be transferred over greater distances, can be transformed
What are the three causes of opposition to current flow in an AC circuit?
Inductive reactance, capacitive reactance, resistance
Ability of a coil to produce a Back EMF
What component creates capacitance in an AC circuit?
How does a capacitor store electricity?
Stored in the form of electrostatic charge (in a field that exists between two conductors separated by an insulator
What property of an AC circuit is defined by the term "impedance"?
Total opposition to current in an AC circuit
What are two reasons that might cause a nickel-cadmium battery to fail in delivering its rated capacity?
Faulty cells or cell imbalance
What electrical values are measured by a typical multi-meter?
voltage, current, resistance
What are five sources of electrical energy?
Magnetism, chemical energy, light, heat, and pressure.
What four things affect the resistance of an electrical conductor?
The material, the cross-sectional area, the length, and the temperature.
How can you tell the resistance of a composition resistor?
By a series of colored bands around one end of the resistor.
How can you find the polarity of an electromagnet?
Hold the electromagnet in your left hand with your fingers encircling the could in the directions the electrons flow. Your thumb will point to the north end of the electromagnet.
In what units is impedance measured?
What happens to the current in a DC circuit if the voltage is increased but the resistance remains the same?
The current increases.
How is a lead-acid battery compartment treated to protect it from corrosion?
Paint it with an asphaltic (tar-base) paint or with polyurethane enamel.
What is used to neutralize spilled electrolyte from a lead-acid battery?
A solution of bicarbonate of soda and water