ATP 106 Final Prep

Why do static charges accumulate on insulator materials only?

Because insulators hold the electrons in position.

Why is static electricity considered to be a charge and not a current?

Because the electrons are sitting still and not moving.

Alternating current is described as _____.

Bidirectional

What is a group of cells connected together called?

Both a battery and a voltaic pile

What is the negative terminal of a power source called?

Cathode

Grounding(ed)

Connected to a ground rod and/or the grounding terminal of a receptacle supplied by an equipment grounding conductor

Coercive Force

measure of a material's ability to retain magnetism

Permeability

measure of a material's willingness to become magnetized

Flux Density

measure of the strength of a magnetic field

What is the positive terminal of a power source called?

Anode

An inductor has an inductance of 0.025 H and a wire resistance of 3 Ω. How long will it take the current to reach its full Ohm's law value?

(H/R) x 5 Henrys x Resistance x time phases (exp. curve) .0417 seconds

An inductor has an inductance of 0.125 H and a wire resistance of 7 Ω. How long will it take the current to reach its full Ohm's law value?

(H/R) x 5 Henrys x Resistance x time phases (exp. curve) .0893 seconds

What is the Voltage produced by a Silicon Solar Cell?

0.5 V

Describe a ground-fault current path

1) A low-impedance path to facilitate the operation of an overcurrent protective device 2) A conductor large enough not to overheat and burn off 3) All the branch-circuit conductors run in the same conduit or cable

What are the requirements for installing conductors in parallel?

1) All circuit conductors are the same size in circular mil area. 2) All circuit conductors are of the same conductor material. 3) The conductors are of the same length.

What is a "conducting body that extends the ground connection"?

1) It is a grounding electrode consisting of the structural metal frame of a building. 2) It is conduit or wire that extends from the point where an "earth connection" is made. 3) It is an 8 ft ground rod with a resistance of 25 ohms or less.

How would one describe an electrical system?

1) The energy supplied by a generator is a system. 2) The electric utility supplies the system at the service to the building. 3) The energy supplied by a solar photovoltaic source is a system.

The equipment grounding conductor:

1) connects equipment to the system ground conductor 2) connects normally non-current-carrying metal parts together 3) connects equipment to the grounding electrode

Three 12-V, 100 Amp hour batteries are connected in PARALLEL. What are the output Voltage and Amp hour capacity of this connection?

12 Volts, 300 Amp hour

A battery is rated for 4 amp hours. How many hours will it last if it is tested to be producing 2 amps? 5 amps?

2 amps = 40 hours 5 amps = 16 hours

A force of 1 ounce is equal to how many dynes?

27,800

Three 12-V, 100 Amp hour batteries are connected in SERIES. What are the output Voltage and Amp hour capacity of this connection?

36 Volts, 100 Amp hour

Into how many time constants is an exponential curve divided?

5

A battery is rated for 4 amp hours. How many amps can it produce for 5 hours? for 30 hours?

5 hours = 1 amp 30 hours = 6 amps

A 6-V Lead-Acid battery has an Amp hour rating of 180 Amp hours. The battery is to be load tested. What should be the test current and what are the maximum permissible amount and duration of the Voltage drop?

540 Amps, 4.8 Volts

A solar cell can produce a voltage of 0.5 V and has a current capacity of 0.1 A. What voltage and amperage would be generated by the following configuration? Three banks of 12 cells connected in series. Each bank should then be connected in parallel.

6 V , 0.3 A

Each time constant of an exponential curve is equal to what percentage of the maximum amount of charge?

63.2%

An example of a separately derived system

A 1-phase generator connected to the electrical system by a 3-pole transfer switch

What is a secondary cell?

A cell which can be recharged

What is a primary cell?

A cell which cannot be recharged

What is an electroscope?

A device used to test the electrostatic charge of a material.

What is a voltaic cell?

A device which converts chemical energy into electrical energy

Grounded Conductor

A system or circuit conductor that is intentionally grounded

What are the three basic substances that can be used to produce ionization in a liquid?

Acids, Alkalines, and Metallic Salts

What is used as the Electrolyte in a Carbon-Zinc cell?

Ammonium Chloride, Manganese Dioxide, and Granulated Carbon

The amount of current the battery can produce for a period of 20 hours at 80 degrees Fahrenheit is known as what?

Amp Hours

What electronic component is often used to prevent large voltage spikes from being produced when the current flow through an inductor is suddenly terminated?

Diode

Choose the two factors that determine the speed an electron attains inside a gas environment.

Distance traveled, Applied Voltage

Find R given E and I

E/I

Find I given E and R

E/R

Find P given E and I

EI

What part of an atom has a negative charge?

Electron

What is the most important factor in the ionization of a gas?

Electron Impact

What are the three principal parts of an atom?

Electron, Neutron, and Proton

Electrical current is the flow of _____.

Electrons

What special property does the material used in aluminum drums have that makes it useful in a copy machine?

Its conductivity changes with a change in light intensity.

* Find P given I and R

I² × R

* Find R given E and P

E²/P

* Find P given E and R

E²/R

A thundercloud has a negative charge, and an object on the ground has a positive charge. Which way will the lightning discharge?

From the cloud to the ground

Examples of electrical energy for the electrical system

Fuel cell, utility-supplied service, and solar photovoltaic system

Find E given I and R

IR

The amount of voltage required to start conduction in a gas is called what?

Ionization Potential

Conduction in a liquid depends on the movement of what?

Ions

What materials are used in the construction of a Type J thermocouple?

Iron and Constantan

Which device is used for lightning protection?

Lightning arrestors and Lightning rods

What were early natural magnets known as?

Lodestones

What is the advantage of the Alkaline Cell as compared with the Carbon-Zinc Cell?

Longer life

How would one describe an effective ground-fault current path?

Low-impedance, continuous and reliable, intentionally constructed

What material is used as the positive electrode in an Alkaline Cell?

Manganese Dioxide

What material is used as the positive electrode in a Zinc-Mercury cell?

Mercuric Oxide

What is an atom which has gained one or more electrons?

Negative

What part of an atom has no charge?

Neutron

A conductor is made from a material that contains between _____ valence electrons.

One and Three

Find I given P and E

P/E

Find E given P and I

P/I

* Find R given P and I

P/I²

If electrons are removed from an object, is the object positively or negatively charged?

Positive charge

An electroscope has been charged with a negative charge. An object with an unknown charge is brought close to the electroscope. The leaves of the electroscope come closer together. Does the object have a positive or a negative charge?

Positive charge.

What determines the density of the molecules in a gas environment?

Pressure

What does the word piezo mean?

Pressure

What part of an atom has a positive charge?

Proton

What happens if the south pole of one magnet is brought close to the south pole of another magnet?

Repel each other

A basic law of physics states that like charges _____ and opposite charges _____.

Repel; Attract

Reluctance

Resistance to magnetism

What type of material is used to coat the aluminum drum of a copy machine?

Selenium

An insulator is a material containing _____ valence electrons.

Seven or Eight

Is the north magnetic pole of the earth a north polarity or a south polarity?

South Polarity (magnetic)

Bonding(ed)

The permanent joining of metallic parts to form an electrically conductive path

What determines the polarity of magnetism when current flows through a conductor?

The direction of current flow

The definition of ground:

The earth

What determines the thickness of the coating during an electroplating process?

The length of time

What factors determine the amount of voltage produced by a cell?

The materials

What determines the amount of current a cell can provide?

The size

What determines the current capacity of a Solar Cell?

The surface area of the solar cell

What determines the color of light emitted by a gas-filled tube?

The type of gas

What determines the amount of voltage produced by a thermocouple?

The type of material and the difference in temperature between the junction and open ends.

Can one thundercloud contain both positive and negative charges?

Yes

What is used to hold a sulfate ion together?

Two extra electrons

A thermocouple is to be used to measure a temperature of 2800°F. Which thermocouple is qnot used to measure this temperature?

Type J

Direct current is described as _____.

Unidirectional

How can the polarity of an electromagnet be determined if the direction of current flow is known?

Using the left-hand rule

Residual Magnetism

amount of force remaining in a material after the magnetizing force has been removed

Equipotential bonding means:

connecting equipment together to reduce shock hazards

The system bonding jumper:

is installed at a separate derived system, provides a path for fault current to flow, and is similar in function to the main bonding jumper.

Inverse-time

the more current that flows in the circuit, the less time it will take for the overcurrent device to operate.

Saturation

the point at which a further increase in magnetizing current causes a minimal increase in the magnetic field strength of an electromagnet

In its simplest form, bonding means:

the same thing as grounding.

* Find I given P and R

√(P/R)

* Find E given P and R

√(PR)