Chapter 6: Electricity

What are the way that will step down the current in a transformer?

10 loops in the primary coil compared to 5 in the secondary coil; 10 loops in the primary coil compared to 2 in the secondary coil

field-particle model

A complex and highly mathematical explanation of attractive and repulsive forces; forces attributed to rapid emission and absorption of subatomic particles.

Thomas Edison

He built the first electric generator. He studied both ac and dc systems, but chose dc for large-scale electrical networks because of the advantages it offered at the time.

action-at-a-distance model

Recognizes masses are attracted gravitationally, and electric charges and magnetic poles attract and repel through space.

What are the components of a typical electric circuit?

a device in which work is done; a device that creates a higher electrical potential

A short circuit can happen when ______

a new lower-resistance pathway becomes available to complete the circuit

The electric current of one coulomb per second is defined as one _____

amp

A(n) ______ charge resides on an object and is the result of a gain or loss of electrons.

electrostatic

In an electric circuit, the rate of current (amps) ______ to the difference in the electrical potential (volts) between two parts of the circuit.

is directly proportional

The unit of work is the ______

joule

The ratio of 1 volt 1 amp defined the unit of resistance called an ______

ohm

It is easier to build up an electrostatic charge (static electricity) on days with low humidity because ______.

on humid days the electrons flow at a greater rate between charged objects

The Earth's magnetic field is shaped and oriented as if ______

there were a huge bar magnet inside the Earth

The _______ of the Earth's iron and nickel outer core likely causes Earth's magnetic field.

flow

True or False: Electrons move around an atom and always remain with that atom.

False

True of False: The fundamental charges of an electron and proton differ in sign but have the same absolute value.

True

True or False: The cost of running an electric appliance can be predicted.

True

The electric potential ______ when two like-charged particles move away from one another.

decreases

Magnetism is though to be produced by _____.

electric currents

The alignment of enough of a metal's ______ in one direction can be caused by exposure to a magnetic field; this can cause the metal to become magnetic.

magnetic domains

Electricity is likely the cause of _____.

magnetism

The mineral ____ is composed of iron oxides and strongly attracts iron and steel.

magnetite

An atom that loses or gains electrons from its neutral state is said to be ionized. If it gains electrons from the neutral state, it will be a ______ ion.

negative

An unknown charge attracts an approaching test charge; therefore, the unknown charge must have a _____ charge.

negative

A transformer works by passing a current in a primary coil which produces a magnetic field that grows and collapses. This pulsing magnetic field induces a current in a secondary wire coil. The transformation of the voltage comes from the difference in the ______.

number of loops between the primary and secondary coils

In electrical terms, a watt is measurement of _____.

power

The voltage multiplied by the charge divided by time is equal to electrical ______.

power

What are the factors that affect electric current when a voltage is applied to a conductor?

the cross-sectional area of the conductor; the drift velocity; number of free electrons per unit volume

What two factors influence the size of the electrostatic force between two charged objects (Coulomb's law)?

the distance between them; the amount of charge on each object

What are the things that effect of adding more resistances in a parallel circuit?

there will be an increase in the current in the circuit; the same voltage is maintained across each resistance; there will be a lower total resistance for the entire circuit

Hans Christian Oersted discovered that an electric current ____.

produces a magnetic field

There seems to be a relationship between the rate of rotation of a planet and the strength of its magnetic field. The fast the rotation, the _____.

stronger the magnetic field

The difference between the ac electric motor and a dc electric motor is the direction of the electric current in the armature _______.

switches directions every half-turn in the dc motor

You can see the speakers in a larger sound system moving because ______.

that is how they produce sounds: by moving forward and back creating condensations and rarefactions

Exposing an unmagnetized piece of iron to a magnetic field may cause it to become magnetic by _______.

the alignment of the majority of the iron's magnetic domains in one orientation

What is true about magnetic poles?

unlike magnetic poles attract each other; like magnetic poles repel each other

Ignoring resistance, electric ______ can be measured where a voltage source creates a potential difference by doing work to move charges to a higher potential.

work

Electrons have a _______ charge and protons have a _______ charge.

negative; positive

When a potential difference is applied to a wire in a circuit, the random motion of the electrons in it changes to a zigzag with a net motion in one direction. This added motion is called the ______ velocity.

drift

A moving or flowing charge is known as a(n) _____ current.

electric

An electric charge produces a force field in the space around it. Since the field is the result of electric charge, we call the force field a(n) ______ field.

electric

A galvanometer measures _____.

electric currents by reacting to the magnetic fields they produce

Test charges are used to identify the _____.

electric field that surrounds the space of an electric charge

An electric motor works by converting _______ energy to ______ energy.

electrical; mechanical

Electricity involves the movement of _____ from atom to atom.

electrons

The difference between direct and alternating currents is the current moves _______

in one direction in direct current and switches the direction of motion in alternating current

The electric potential _______ when work is done moving two like-charged particles near each other.

increases

An electric generator produces electricity by ______.

inducing a voltage in a wire by rotating an axle wrapped in wire within a magnetic field

Holding an electrostatically charged object near a material with a random distribution of electrons can result in the material's electrons becoming reoriented; this process is called _______.

induction

Forces of attraction seem to be concentrated around the ends, or the two _____ poles, of a magnet.

magnetic

George Westinghouse

He supplied gas for lighting but promoted ac to replace gas as the source of electricity for large-scale electrical networks.

Nikola Tesla

Holds the number of complicated patents for the generation, transmission, and use of ac electricity.

Electric circuits use either alternating current (ac) or direct current (dc). What are the circuits that most commonly use direct current?

a wireless mouse for a computer; cell phones

Masses and electric charges both ______.

affect the space around them

The word electricity is based upon the Greek word for _____

amber

Substances that have magnetic properties (ferromagnetic properties) are ones that ______

are strongly attracted to magnets

The magnetic field lines around the air producing a magnetic field are drawn ______.

at right angles to the length of the wire

A polarized household plug is one where one of the two prongs is larger than the other one. The purpose of the large prong is to _______.

be a safety device as it serves as a ground or neutral

What are the processes by which an object can become electrostatically charged?

by contact; by induction; by friction

What are the two ways that an electric potential difference can be measured?

by the work that is done to move the charge; by the work that the charge can do because of its position

Strong magnetic fields are represented by drawing magnetic lines ______.

closer together

In a transformer, the difference in the number of _______ between the primary and secondary coils determines the voltage difference.

coils

Materials that have electrons that are free to move about are called ______ and those that do not are called ______.

conductors; insulators

What are the variables on which electrical resistance of a dc circuit depends?

diameter; temperature; material; length

The magnetic _______ is the angle between the horizontal and the downward angle of a compass needle that is free to pivot.

dip

If the source that is generating an electric field disappears, the electric field will ____.

disappear but over time

What is true regarding the charge of protons and electrons?

electrons and protons cannot be separated from their charge; protons have a positive charge; the charge of protons and electrons is opposite

What are the problems with viewing electric current as a fluid?

electrons are not pushed out one end as more come in the other end of a wire; electrons do not move in a wire just as water does in a pipe

The quantity of charge (q) is equal to the number (n) of _______ multiplied by the ______ (e) of one of them.

electrons; charge

A ______ works by disconnecting a circuit if the circuit tries to draw more than a preset amount of amps.

fuse

The Earth's magnetic field _____.

has undergone polarity reversals where the north magnetic pole is at the south geographic pole

The angle difference between the magnetic north pole and the geographic North Pole is called ______

magnetic declination

The tiny region in a material where atoms are magnetically aligned is called the _____

magnetic domain

A ground-fault interrupter works by breaking the circuit faster than a fuse or circuit breaker can by ______.

noting a current difference between the load-carrying wire and the system ground wires

The conventional model describes a _____ charge moving from the positive to the negative terminal of a battery, and the electron current model describes current as the drift of _____ charges that flow from the negative to the positive terminal.

positive; negative

Atoms are made of three basic particles. They are ______ and neutrons in the nucleus and _______ moving around the nucleus at a distance from it.

protons; electrons

Electric current (I) is equal to the _______.

quantity of charge divided by time

An electromagnetic device that uses a low-voltage control to switch a larger, high-voltage circuit on and off is called a ______

relay

If two charges of the same sign are pushed toward one another, the resulting force will be ______.

repulsive

The electric potential difference (V) divided by the current (I) is equal to the _____

resistance

The property of opposing or reducing a current is known as electrical ______

resistance

Materials that sometimes conduct electricity and sometimes insulate, depending on conditions and their purity, are called ____.

semiconductors

If the negative terminal of one battery cell is connected to the positive terminal of another battery, it is a _____ circuit. If all positive terminals are connected and all negative terminals are connected, it is a ____ circuit.

series; parallel

Many loops of wire formed into a cylindrical coil are called a _____.

solenoid

An electric circuit contains some device in which work is done, and therefore must contain a device that gives the _______.

source of energy to move the charges to a higher potential against an electric field

In an electric circuit, the source of the electrical potential is called the voltage ______, and the device where the charges do work is called the voltage ______.

source; drop

The south pole of a magnet will seek the magnetic ______ pole of the Earth.

south

If the electric field potential goes to zero, the electric current will ______

stop

How are electric fields represented?

stronger fields are represented by drawing lines closer together; they are represented by lines that show the direction of the field

What statements summarize the nature of electric currents?

the average velocity of the electrons moving as a current is very slow but the electric field moves at close to the speed of light; an electrical potential creates, at nearly the speed of light, a electric current; the electric field causes a net flow of charge or current

What are the factors that affect the magnitude of the induced voltage in a wire during an electromagnetic induction?

the number of wire loops passing through the magnetic field lines; the strength of the magnetic field; the rate at which the magnetic field lines pass through the wire

The total resistance in a series circuit of resistors is equal to ______.

the sum of all the resistors in the series

The electric potential difference (volt) is equal to _____

the work to create the potential divided by the charge moved

The drift velocity of electrons in a wire is ____.

the zigzag movement that results in a net motion in one direction

An electromagnet can be produced by passing a current ______.

through the wires of a solenoid

A device used to step up or step down the ac voltage in a circuit is called a ______

transformer

A single bar magnet with one north and one south pole is broken in half to make two pieces. The result is _____.

two magnets each with a north and south pole

An electrical force (or electromotive force) is also called the ______.

voltage

Ohm's law shows the current multiplied by the resistance is equal to the _____.

voltage

Electromagnetic induction occurs when a loop of wire is moved in an electric field or when an electric field in range of a wire is changed. Either of these two actions will produce a _______ in the wire and this will induce a _______ in the wire.

voltage; current

If 2.00 joules of work is done moving a charged particle against an electric field, the potential energy that now exists with the charged particle is _____.

2 joules

field model

Considers a field to be a condition of space around a mass electric charge, or magnet; field properties described by field lines.