Module 4

What's a property of matter?

Charge

An electrical device with a deficiency of electrons will do which of the following when grounded?

Take on electrons until neutral

Coulomb

The SI unit (abbreviated as C) equal to the electrical charge of 6.25 x 10^18 electrons. This is a negative number for a negative charge; a positive charge of 1 C is equal to the same number of protons.

What are electrical charges measured in?

The SI unit called the coulomb.

The ampere

The SI unit for charge per second, sometimes just called an "amp." One ampere equals one coulomb flowing by in one second: Amperes=coulomb/second

Ampere

The SI unit for current flow (abbreviated as A), or amount of charge per second, or how many electrons are flowing past a particular point in the current in 1 second; 1 A equals 1 coulomb flowing by in 1 second.

Joule

The SI unit for energy, the ability to do work. One joule of electrical energy is the same as one joule of mechanical energy—it is just energy in a different form.

Momentarily stores electric charge?

Capacitor/Condensor

How many general laws or principles of electrostatics?

Five

How are amperage and voltage related?

Amperage and voltage are inversely related; as one goes up, the other goes down

What happens to the electric potential as the electric field increases?

Increases

General Laws of Principles of electrostatics?

-Like charges repel and unlike charges attract each other. -The electrostatic force between two charges is directly proportional to the product of their quantities and inversely proportional to the square of the distance between them (aka Coulomb's Law). -Electric charges reside only on the external surface of conductors. -The concentration of charges on a curved surface of a conductor is greatest where the curvature is greatest. -Only negative charges (electrons) are free to move in solid conductors.

Electrification by contact occurs when?

A charged object touches an uncharged object and the latter acquires the same charge; occurs by touching the object so that the charge transfers to it. This is what happens when your charged fingertip touches a doorknob and the charge moves to the metal and creates a spark.

Cross-sectional area:

A conductor with a large cross-sectional area will have a lower resistance than one with a small cross-sectional area because there is a greater external surface area on which electrons can travel.

Circuit breaker

A device that acts in the same manner as a fuse. If the current flowing through it rises above a certain level, the circuit breaker flips its internal switch to open the circuit and stop the electric flow. After the problem is corrected, the circuit breaker can be switched back on. Circuit breakers protect against short circuits and shock hazards.

How voltage and amperes are related?

A low-voltage, high-amperage current has many electrons moving but a low-amperage, high-voltage current with fewer electrons moving may be just as powerful because of the higher potential.

Conductor

A metal or other substance with electrons that are free to produce a current.

The second condition needed for currents to flow?

A pathway for the electrons to travel. Metals and other substances that provide good pathways are called conductors.

Insulators

A substance that does not conduct electric current because its electrons are bound within the molecules and cannot freely move.

Diode

Allows electrons to flow in one direction.

The standard electricity that flows into your home?

Alternates back and forth at 60 cycles per second.

The SI unit for charge or current flow per second is:

Ampere.

When an electric potential exists?

An electric current, or a flow of electrons, occurs in a conductive metal or other substance.

Electrical equipment using a three-prong plug.

An example of grounded

The earth is essentially an infinite reservoir of electrons.

Any charged object can be neutralized if it is grounded. Positively charged objects will take on electrons from the earth, and negatively charged objects will give up electrons to the earth until neutral.

Why do we base the measure of electric charge on electrons?

Because in a solid conductor, they are free to move.

An object may be electrified in three ways:

By friction, by contact, and by induction.

Volt

Defined as the potential difference that will maintain a current of one ampere in a circuit with a resistance of one ohm. The current passing through a conductor. Refers to the difference in electric potential between the two charges that make the current flow

What are required for electric current to exist?

Electric potential difference and Suitable medium in which to travel

What's the smallest units of charge?

Electrons and Protons

Electrification by friction occurs when?

Electrons are rubbed off one object and deposited on another. This is what happens when you rub the balloon on your hair to create static electricity.

Good conductors contain?

Electrons that are not tightly bonded to their atoms.

A section of special wire, usually encased in glass, that quickly melts if the current flowing through it rises too high.

Fuse

In which media will ions drift towards the oppositely charged electrode?

Gas and Ionic Solution (In both a gas and an ionic solution, the positively charged ions will drift to the negative electrode, and the negatively charged ions will drift to the positive electrode. )

Example of good insulators?

Glass, ceramic, wood, plastic, and rubber are all good insulators. Glass or ceramic are often used atop power poles to hold the power lines. Plastic is the typical coating for electric cords on electrical devices.

Electric potential

Glossary : Potential energy per unit charge. In a battery, for example, many electrons are crowded together at the negative battery terminal. The potential is the difference between the energy per charge at the negative end and the energy per charge at the positive end.

Insulators

Help contain electricity flow. Insulating material such as rubber or plastic is often used to surround electrical wires or components. Insulators are used to prevent the electric current inside from flowing to an unintended place, such as your hand

Electric current behaves differently depending on the medium in which it travels:

In a vacuum tube, the electrons tend to jump the gap between oppositely charged electrodes (e.g., x-ray tube). In a gas, the positive ions (usually present in a gas) will drift towards the negative electrode, and the negative ions will drift towards the positive electrode (e.g., neon light). In an ionic solution such as salt water, the positive ions move to the negative electrode and the negative ions to the positive electrode (e.g., salt water will separate into component ions). In a metallic conductor, electrons from the conductor's atoms will move out of the valence shell to a higher energy level just beyond, called the conduction band, where they are free to drift along the external surface of the conductor (e.g., copper wire).

Most nonmetallic elements do not conduct electric current because?

In the atoms of nonmetallic elements, the electrons are generally bound within the molecules and cannot move freely to produce a current, even when attracted by a potential difference.

Transformer

Increases or decreases voltage by fixed amount

What's a poor conductor of electricity?

Insulators because they have virtually no free electrons

The production of x-rays, is achieved by?

Manipulating electricity

Conductors and examples?

Materials that allow a relatively free flow of electric current. Metals such as Copper, which is one of the most common because it has an abundance of free electrons. Aluminum, gold and Water because of the mineral impurities it often contains.

Ammeter

Measures electric current.

The same is true of an electric field:

Move the two charged objects three times as far apart, and the force will be one-ninth of what it was when it was closer.

What will move in solid conductors?

Negative charges

What will move in solid conductors?

Negative charges/electrons

A conductive substance is?

One with free electrons that allow the flow of a current.

What's a common insulator?

Plastic because it has few free electrons and, therefore, does not allow current to flow.

Battery

Provides electrical potential.

According to Coulomb's Law, what will happen to the electrostatic force between two charges if the distance between them is cut in half?

Quadruples. Increases four times.

Length:

Resistance is directly proportional to the length of the conductor; that is, a long conductor has more resistance than a short one.

Variable resistor

Rheostat

Material

Some materials will allow for a free flow of current because they have an abundance of free electrons (conductors discussed in Section 4) while other materials have tremendous resistance because they have virtually no free electrons (insulators discussed in Section 4).

Ground

Something that is able to absorb electrical charges. A process of connecting the electrical device to the earth via a conductor.

Ohm

The SI unit of measure for resistance, shown by the Greek letter omega. Named for the physicist George Simon Ohm who discovered the inverse relationship between current and resistance. One ohm is defined as the resistance of a standard volume of mercury (14.45 g column, 106.3 cm long) under standard conditions (uniform cross-sectional area at 0° C).

Resistance

The ability of an element in a circuit to resist the flow of electricity by reducing or impeding it. The higher the resistance, the lower the current; the lower the resistance, the higher the current.

Potential energy

The ability to do work by virtue of state or position.

Electric potential

The ability to do work due to separation of charges. (measured in Volts) The greater the electric potential, as the electric field is increased, the greater the potential energy and the greater the electric current once it starts flowing.

Charles Coulomb first described?

The amount of electrostatic force between two objects depends on the amount of electrical charge in each (product of their quantities) and the distance between them (inversely proportional to the square of the distance). This relationship is demonstrated mathematically as F = k (Q1 x Q2/r2) where Q1 and Q2 are the quantities, r is the distance and k is the electrostatic constant (9.0 x 109Nm2/c2).

The inverse square law says that ?

The amount of light in the same area three times as far away will be one-ninth, because the light spreads out as it radiates from the source.

Electric circuit

The closed pathway of an electric current. The total pathway of the electric current, through whatever kinds of devices and wires

Electrification

The condition of an object that has gained a charge through friction, contact, or induction. In electrostatics, electrification of objects occurs when they gain either a net positive or a net negative charge.

What causes electric currents to flow?

The forces of attraction and repulsion are also what cause electric currents to flow, and this is the electric potential difference.

The term Volt came from?

The name of the Italian physicist, Volta, who invented the battery two centuries ago. This unit is a measure of the difference in electric potential between two points. The volt is equal to the amount of work (joules) that can be done per unit of charge. Volts are measured as the ratio of joules (energy) to coulombs (charge): volts = joules/coulombs.

Electric current takes which path?

The path of least resistance; the current can be very high and cause rapid overheating and fire.

Ohm's Law states that?

The potential difference (voltage) across the total circuit or any part of that circuit is equal to the current (amperes) times the resistance. It is expressed by the formula V= IR, where V is voltage, I is current, and R is resistance.

Define Electrodynamics and example?

The principles of electrical charges in motion or the study of electric charges in motion. The flow of electrons in a conductor.

Define Electrostatics and example?

The principles of nonmoving electrical charges or study of stationary electric charges. Or electrical charges at rest. The positive charge in the nucleus of an atom.

Electrification by induction is?

The process by which an uncharged metallic object experiences a shift of electrons when brought into the electric field of a charged object. Induction occurs as a result of the interaction of the electric fields around two objects that are not in contact. GLOSSARY (it occurs when one charged object attracts the opposite charges or repels similar charges in another object and thereby electrifies that area of the other object.)

Current

The stream of electricity that moves along a conductor (Symbol I). An electric current is due to a difference of potential between two points, this difference being measured in volts. The volume of flow depends on the difference of potential and the resistance to be overcome and is measured in amperes. The quantity of current is measured in coulombs electric current The actual flow of electrons in a conductor.

Alternating current (AC)

The type of current in which electrons alternate direction of flow as the electric potential switches back and forth.

Direct current (DC)

The type of current that flows in only one direction; the current produced by batteries. The kind of current produced by batteries.

Voltage (2)

The unit of measurement (abbreviated as V) for electric potential; the difference in electric potential between two points. (an expression of electrical potential)

Protective electrical devices

They protect the circuit and human beings around it.

The ability to do work due to separation of charges?

Volts

Which of the following is measured as the ration of energy(Joules) to charge(Coulombs)?

Volts

The concentration of charges on a curved surface of a conductor will be the greatest:

Where the curve is the greatest.

Temperature:

With metallic conductors, the resistance becomes greater as the temperature of the conductor rises.

Units of measure for electricity?

conductors, insulators, and electrical devices

Which of the following will have the greatest resistance?

material with few free electrons, high temperature, small cross-sectional area, and long conductor length.

The amount of resistance of a conductor depends on four things:

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

Properties of electricity?

voltage, current, and resistance

measure electric potential

voltmeter