Fundamentals of Electricity and Electrons

Question 1

What is the basic unit of voltage?

Answer 1

The volt.

Question 2

Why should electrolytic capacitors not be used in an AC circuit?

Answer 2

They are polarized. An electrolytic capacitor will pass current of one polarity, but will block current of the opposite polarity.

Question 3

What is the basic unit of current?

Answer 3

The amp.

Question 4

What is meant by inductance?

Answer 4

The ability to store electrical energy in electromagnetic fields.

Question 5

What is the basic unit of resistance?

Answer 5

The ohm.

Question 6

Which law of electricity is the most important for an aircraft mechanic to know?

Answer 6

Ohm’s law.

Question 7

What are the three elements in Ohm’s law?

Answer 7

Voltage, current, and resistance (volts, amps, and ohms).

Question 8

What are five sources of electrical energy?

Answer 8

Magnetism, chemical energy, light, heat, and pressure.

Question 9

What four things affect the resistance of an electrical conductor?

Answer 9

The material, the cross-sectional area, the length, and the temperature.

Question 10

How can you tell the resistance of a composition resistor?

Answer 10

By a series of colored bands around one end of the resistor.

Question 11

What three things must all electrical circuits contain?

Answer 11

A source of electrical energy, a load to use the energy, and conductors to join the source and the load.

Question 12

What is the purpose of a capacitor?

Answer 12

To store electrical energy in electrostatic fields.

Question 13

What is the basic unit of capacitance?

Answer 13

The farad.

Question 14

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

Answer 14

The watt.

Question 15

What is meant by a kilowatt?

Answer 15

1,000 watts.

Question 16

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

Answer 16

The current increases.

Question 17

What are three types of DC circuits, with regard to the placement of the various circuit components?

Answer 17

Series, parallel, and series-parallel.

Question 18

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

Answer 18

12.

Question 19

What is the specific gravity of the electrolyte in a fully charged lead-acid battery?

Answer 19

Between 1.275 and 1.300.

Question 20

What is the basic unit of inductance?

Answer 20

The henry.

Question 21

What is meant by impedance?

Answer 21

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

Question 22

How can you find the polarity of an electromagnet?

Answer 22

Hold the electromagnet in your left hand with your fingers encircling the coil in the direction the current flows. Your thumb will point to the north.

Question 23

In what units is impedance measured?

Answer 23

In ohms.

Question 24

What is the range of temperature for a lead-acid battery that does not require a correction when measuring its specific gravity?

Answer 24

Between 70 degrees and 90 degrees Fahrenheit.

Question 25

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

Answer 25

A hydrometer.

Question 26

How is a lead-acid battery compartment treated to protect it from corrosion?

Answer 26

Paint it with an asphaltic (tar base) paint or with polyurethane enamel.

Question 27

What is used to neutralize spilled electrolyte from a lead-acid battery?

Answer 27

A solution of bicarbonate of soda and water.

Question 28

How high should the electrolyte level be in a properly serviced lead-acid battery?

Answer 28

Only up to the level of the indicator in the cell.

Question 29

What precautions should be taken in a maintenance shop where both lead-acid and nickel-cadmium batteries are serviced?

Answer 29

The two types of batteries should be kept separate, and the tools used on one type should not be used on the other.

Question 30

Why is a hydrometer not used to measure the state of charge of a nickel-cadmium battery?

Answer 30

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.

Question 31

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

Answer 31

A solution of boric acid and water.

Question 32

What is meant by electromagnetic induction?

Answer 32

The transfer of electrical energy from one conductor to another that is not electrically connected.

Question 33

How many ohms are in a megohm?

Answer 33

One million (1,000,000).

Question 34

What part of an amp is a milliamp?

Answer 34

One thousandth (1/1000).