EIT 115 - Exam 1 Review

The Greeks were the first to discover electricity about ___________ years ago.

2500

Direct current is described as?

Uni-directional

There is very little resistance and a large amount of current flows in a _______________ circuit.

Short

Copy machines operate on the principle of static electricity. True or False?

True

Earth contains magnetic poles. True or False?

True

The amount of electrical power being used in a circuit is measured in?

Watts

What force is demonstrated in objects with unlike charges?

Attraction

What is the maximum number of valence electrons in an atom?

Eight

What type of magnet depends on flowing current to produce a magnetic field?

Electromagnet

A thundercloud contains only positive electric charges. True or False?

False

During normal operation of a typical 120-volt appliance circuit, current flows through the hot, grounding, and neutral conductors. True or False?

False

In electrical schematics, the symbol used to represent a resistor is standard. True or False?

False

Matter can exist in only two states: solid or liquid. True or False?

False

What are the 3 principle parts of an atom?

1. Electron 2. Neutron 3. Proton

An electrical circuit has a voltage of 50 V and a resistance of 5 ohms. What is the value of current?

10 A

Approximately how many horsepower is an electrical device listed as 3,000 watts?

4

An electric motor is running on 120 V. The current is measured to be 2 A. How many ohms of resistance is the motor?

60

A precipitator is a type of _________________.

Air filter

What type of current reverses its direction of flow at regular intervals?

Alternating

The strength of an electromagnet is primarily proportional to its ________________________.

Amere-turns

What is the smallest part of an element that still retains the properties of that element?

An atom

Static electricity refers to electrons that are or are not moving?

Are not

A lightning protection device that is grounded at one end, with the other end close to but not touching the object to be protected, is called a lightning _____________.

Arrestor

Alternating current is described as?

Bi-directional

What type of fixed resistor is made by applying a film of carbon to a ceramic rod?

Carbon film

A complete circuit is often referred to as a _____________ circuit.

Closed

What type of fixed resistor is made from a compound of carbon graphite and resin bonding material?

Composition carbon

What law states that the force of electrostatic attraction or repulsion is directly proportional to the product of the two charges and inversely proportional to the square of the distance between them?

Coulomb's Law

The angular difference between true north and magnetic north is known as the angle of?

Declination

If an object is placed in the field of a strong electromagnet connected to an AC line, the object will be __________________.

Demagnetized

What type of current flows in only one direction?

Direct

The regions formed in the molecular structure of magnetic metals are sometimes called magnetic __________________.

Domains

Electrical current is the flow of?

Electrons

What type of resistors can only have one ohmic value?

Fixed

Magnetic lines of force are referred to as _____________.

Flux

In the English system of measure, magnetic strength is measured in terms of ____________.

Flux density

A semiconductor contains ________________ valence electrons.

Four

Electrostatic charges occur on ________________.

Insulators

If a permanent magnet is cut into pieces, each piece is or is not a separate magnet?

Is

To locate the north pole of an electromagnet, use the _________- hand rule.

Left

The nucleus of an atom contains _______________.

Neutrons and protons

The unit of resistance to current flow is the _______________.

Ohm

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

One and three

What type of magnets do not require any power or force to maintain their field?

Permanent magnets

The measure of a material's ability to be magnetized is called ___________________.

Permeability

The atomic number of an element is the number of _____________ in the nucleus.

Protons

The measure of a material's resistance to magnetism is known as ______________.

Reluctance

A variable resistor with 2 terminals is called a?

Rheostat

The semiconductor material used as a coating on copy machine drums is ________________.

Selenium

Selenium is a _________________.

Semiconductor

An insulator is a material containing ___________ valence electrons.

Seven or eight

How many color bands are used on resistors that have a tolerance of +/- 20 percent?

Three

The ________ of a resistor indicates the plus and minus limits of a resistor's ohmic value.

Tolerance

An electroscope can be used to determine the polarity of an electrostatic charge. True or False?

True

Lightning is the result of static charges built up in clouds that contain a large amount of moisture. True or False?

True

Lightning rods provide an easy path to ground for current. True or False?

True

Matter has mass and occupies space. True or False?

True

The grounding prong of a plug should never be cut off or bypassed. True or False?

True

The three substances that form natural magnets are?

1. Iron 2. Nickel 3. Cobalt

One coulomb per second is equal to one __________.

Ampere

Magnetism can be explained in terms of _____________ spin patterns.

Electron

What part of an atom has a negative charge?

Electron

Insulators are the only materials that can hold _______________ stationary.

Electrons

Within a lightning bolt, current flows ________________.

From negative to positive

What standard prefix in engineering notation indicates multiplication by 1,000,000,000?

Giga (G)

What color used as the multiplier band means to divide the combined first two numbers by 10?

Gold

If a thundercloud has a positive charge, the current in the lightning bolt will flow from the?

Ground to the cloud

The neutral conductor is also referred to as the ____________ conductor.

Grounded

The velocity of AC through a conductor is ____________ the speed of light.

Less than

Man-made permanent magnets retain their magnetism longer or less than natural magnets?

Longer

A variable resistor with 3 terminals is called a?

Potentiometer

What is another term for a variable resistor?

Potentiometer

What part of an atom has a positive charge?

Proton

What type of circuit generally occurs when the conductors leading from and back to the power source become connected?

Short

The north magnetic pole of a compass needle is attracted to the _______________ magnetic pole of the earth.

South

The value of a resistor can often be determined by the "color code." True or False?

True

What is another term for electromotive force (EMF)?

Voltage

Resistors functioning as ___________ are used in applications involving field-effect transistors (FETs) and multirange voltmeter circuits.

Voltage dividers

Voltage flows through an electric circuit like water flows through a pipe. True or False?

True

The static charge sometimes used during spray painting is an example of a _______________ static charge.

Useful

The amount of potential necessary to cause one coulomb to produce one joule of work is a ___________________.

Volt

Rheostat

A variable resistor with 2 terminals.

Potentiometer

A variable resistor with 3 terminals.

What is the most common method of producing electricity?

Magnetism

Lodestone is a name for a naturally occurring magnetic material that is also called?

Magnetite

In the English system, the total force producing a magnetic field is the _______________.

Magnetomotive force

In a clothes dryer, the greatest static charges generally are built up on ____________ fabrics.

Man-made

What type of fixed resistor is made by applying a film of metal to a ceramic rod in a vacuum?

Metal film

What type of fixed resistor is made by combining metal with glass and then applying it to a ceramic base as a thick film?

Metal glaze

What is indicated by the forth color band on a resistor?

Multiplier

What type of resistor operates by moving the wiper arm with a screw or some number of turns?

Multiturn variable

If a circuit is open, current will or will not flow?

Will not

What type of fixed resistor is made by winding a piece of resistive wire around a ceramic core?

Wire-wound

What type of resistors are generally used when a high power rating is needed?

Wire-wound

An electric circuit has a resistance of 20 ohms. The current is measured to be a 6 A. How many volts are applied to the circuit?

120

A toaster is listed as 1560 W. When it is plugged into a 120 V circuit and starts to make toast, how many amperes will it draw?

187,200

A basic law of magnetism states that unlike poles _________________ and like pole ____________.

Attract, repel

The precipitator uses a high-voltage DC power supply to provide a set of wires with a positive charge and a set of plates with a ________________ charge.

Negative

What part of an atom has no charge?

Neutrons

The shock that results from walking across a carpet and touching a doorknob is an example of a ______________ static charge.

Nuisance

The statement, "In a DC circuit, the current is directly proportional to voltage and inversely proportional to resistance," is known as ________________ law.

Ohm's Law

Bringing a charged test object near the ball of a charged electroscope causes the leaves to move closer together. This indicates that the test object charge is the same or opposite polarity as the electroscope charge?

Opposite

When an object protected by a lightning ______________ is struck by a lightning bolt, it will bleed the lightning discharge to ground before the protected object can be harmed.

Rod

When a magnetic material's molecules are all lined up, and increases in current flow no longer cause increases in magnetic field strength, the material has reached _____________.

Saturation

Most lightning discharges associated with a cloud occur between the cloud and the ground. True or False?

True

The north pole of a compass needle points in the direction of the south geographic pole. True or False?

True

The valence shell of an atom is the _____________ shell.

Outer

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

Repel;attract

What force is demonstrated in objects with like charges?

Repulsion

The amount of magnetism left in a material after the magnetizing force has stopped is called _______________.

Residual magnetism

What causes a wire to become warm when current flows through it?

Resistance

A resistor whose values can be varied over a range of values is called a _____________ resistor.

Variable