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What is the basic unit of voltage?
the volt
What is the basic unit of current?
the amp
What is the basic unit of resistance?
The ohm.

Which law of electricity is the most important for an aircraft mechanic to know?
Ohm's law.

What are the three elements in Ohm's law?
Voltage, current, and resistance (volts, amps, and ohms).

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.

What three things must all electrical circuits contain?
A source of electrical energy, a load to use the energy, and conductors to join the source and the load.

What is the purpose of a capacitor?
To store electrical energy in electrostatic fields.

What is the basic unit of capacitance?
The farad.

Why should electrolytic capacitors not be used in an AC circuit?
They are polarized. An electrolytic capacitor will pass current of one polarity, but will block current of the opposite polarity.

What is meant by inductance?
The ability to store electrical energy in electromagnetic fields.

What is the basic unit of inductance?

The henry.

What is meant by impedance?
The total opposition to the flow of alternating current. It is the vector sum of resistance, capacitive reactance and inductive reactance.

How can you find the polarity of an electromagnet?
Hold the electromagnet in your left hand with your fingers encircling the coil in the direction the electrons flow. Your thumb will point to the north end of the electromagnet.

In what units is impedance measured?
In ohms.

What is the basic unit of electrical power in a DC circuit?
The watt.

What is meant by a kilowatt?
1,000 watts.

What happens to the current in a DC circuit if the voltage is increased but the resistance remains the same?
The current increases.

What are three types of DC circuits, with regard to the placement of the various circuit components?
Series, parallel and series-parallel.

How many cells are there in a 24-volt lead-acid battery?
12.

What is the specific gravity of the electrolyte in a fully charged lead-acid battery?
Between 1.275 and 1.300.

What is the range of temperatures of the electrolyte in a lead-acid battery that does not require that you apply a correction when measuring its specific gravity?
Between 70 degrees and 90 degrees Fahrenheit.

What instrument is used to measure the specific gravity of the electrolyte in a lead-acid battery?
A hydrometer.

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.

How high should the electrolyte level be in a properly serviced lead-acid battery?
Only up to the level of the indicator in the cell.

What precautions should be taken in a maintenance shop where both lead-acid and nickel-cadmium batteries are serviced?
The two types of batteries should be kept separate, and the tools used on one type should not be used on the other.

Why is a hydrometer not used to measure the state of charge of a nickel-cadmium battery?
The electrolyte of a nickel-cadmium battery does not enter into the chemical changes that occur when the battery is charged or discharged. Its specific gravity does not change appreciably.

What is used to neutralize spilled electrolyte from a nickel-cadmium battery?

A solution of boric acid and water.

What is meant by electromagnetic induction?
The transfer of electrical energy from one conductor to another that is not electrically connected

How many ohms are in a megohm?
One million (1,000,000).

What part of an amp is a milliamp?
One thousandth (0.001).

1. What is meant by tolerance on an aircraft drawing?
The allowable plus or minus variation from the dimension given on the drawing.

What is meant by clearance on an aircraft drawing?
The amount of space, or separation, that is allowed between two components or parts.


What information is given in the title block of an aircraft drawing?
The name and address of the company who made the part, the name of the part, the scale of the drawing, the name of the draftsman, the name of the engineer approving the part and the number of the part (the drawing number).


How are dimensions shown on an aircraft drawing?
By numbers shown in the break of a dimension line.

How can you know that the aircraft drawing you are using is the most current version of the drawing?
By the number in the revision block and by the log of the most recent drawings.
How many views can there be in an orthographic projection?
Six.

How many views are used to show most objects in an aircraft drawing?
Three.
What is the purpose of a center line on an aircraft drawing?
This is the line that shows the center of the object in the drawing.
What is a fuselage station number?
The distance in inches from the datum, measured along the longitudinal axis of the fuselage.
Where is the title block normally located on an aircraft drawing?

In the lower right-hand corner of the drawing.

What is the purpose of a cutting plane on an aircraft drawing?
It shows where an object has been cut to allow an auxiliary drawing to be made. The arrows on a cutting plane show the direction the auxiliary drawing is viewed
How is the alternate position of a part shown on an aircraft drawing?
By a thin line made up of a series of long dashes separated by two short dashes.
1. Where must a record be kept of the current empty weight and the current center of gravity of an aircraft?

In the aircraft flight manual or weight and balance records required by 14 CFR ยง23.1583
What is meant by the datum that is used for weight and balance computations?

A readily identified reference chosen by the aircraft manufacturer from which all longitudinal locations on the aircraft are referenced
Why are the distances of all of the items installed in an aircraft measured from the datum when computing weight and balance?

This makes it possible to find the point about which the aircraft would balance (the center of gravity).
What are two reasons weight and balance control are important in an aircraft?
For safety of flight and for most efficient performance of the aircraft.
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