ASA BASIC ELECTRICITY

What is the basic unit of voltage?

The Volt (V).

What is the basic unit of current?

The Amp (A).

What is the basic unit of resistance?

The Ohm (Ω).

What is the basic unit of capacitance?

The Farad (F).

What is the basic unit of inductance?

The Henry (H).

In what units is impedance measured?

In ohms (Ω).

How many ohms are in a megaohm?

One million (1,000,000).

What part of an amp is a milliamp?

One thousandth (0.001).

What is the purpose of a capacitor?

To store electrical energy in electrostatic fields.

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

They're 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 meant by electromagnetic induction?

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

How can you find the polarity of an electromagnet?

Use the Left-Hand Rule (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).

What are the five sources of electrical energy?

Magnetism, chemical energy, light, heat, and pressure (piezoelectric).

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 (color code).

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 paint or with polyurethane enamel.

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

A solution of bicarbonate of soda (baking 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 (or to the recommended level mark).

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 to prevent contamination.

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

A solution of boric acid and water.