Chapter 8

Describe Coulombs law and problems with it

For two charged particles that are much smaller than the distance between them, the force between the two varies directly as the product of their charges and inversely as the square of the separation distance. F= k q1q2/d^2 k=constant q=charge d=distance Coulomb (C)= the unit of charge 1 coulomb is associated with 6.25 billion billion electrons it is the charge of a 100 W bulb for 1 second

Compare/contrast parallel and series circuits

In a series circuit there is only 1 path. meaning if one light bulb goes out, than so do all the other ones. In a parallel circuit each light bulb has its on path. So if one goes off than the others stay on.

Explain what causes electric shock

The damaging effects of a shock are the result of current, not voltage. However, voltage and resistance affect current. The resistance of the human body varies from 100 ohms if soaked with salt water to 500,000 ohms if skin is very dry.

Electric potential energy

The electric potential energy per amount of charge, measured in volts and often called voltage

Electrical resistance

The property of material that resists the flow of an electric current through it, measured in ohms.

Electric Power

The rate of energy transfer, or the rate of doing work; the amount of energy per unit time, which can be measured by the product of current and voltage: Power = current x voltage It is measured in watts (or kilowatts), which 1 A x 1 V = 1 W.

Equations and Units

k= 9,000,000,000 N*m^2/C^2 or 9.0 * 10^9 N*m^2/C^2 Electric potential= electric potential energy/ amount of charge measured in volts V 1 volt = 1 joule/ 1 coulomb current= voltage/resistance, I=V/R -measured in A - amps power=current*voltage measured in Watts W energy= power*time P=IV

Explain why something has electrical potential energy

-A charged particle has electrical potential energy because of its location in the electric field work is required to push a charged particle against the electric field. This work charges the electrical potential energy. If you have twice the charge you have to do twice the work and twice the electrical potential.

Know the formula to find electric potential

-Electric potential= electric potential energy/ amount of charge -the unit of measurement for electric potential is the volt 1 volt= 1 joule/ 1 coulomb electric potential if often called voltage

Tell which direction an electric field goes

-negative charge goes inward, positive goes outward. The direction of force on a positive charge is in the same direction of the electric field

Give examples of voltage sources

-when you have two different potentials, you have a voltage source -no potential difference, no flow of electrons (no current) examples battery outlet

Conductor

Any material having free charged particles that easily flow through it when an electric force acts on them.

electric field

Defined as force per unit charge, it can be considered an energetic "aura"surrounding charged objects. About a charged point, the field decreased with distance according to the inverse square law, like a gravitational field. Between oppositely charged parallel playes, the electric field is uniform

Explain electric power and know formula

Electric power is the rate at which electric energy is converted into another form Power = current X voltage Measured in watts (W)

Coulomb's formula

F= k q1q2/d^2 k=constant q=charge d=distance measured in C Coulombs

Compare and contrast insulators and conductors

Insulators - materials that prevent the free flow of electrons from atom to atom and molecule to molecule. Examples are plastics, stryofoam, paper, rubber, glass and dry air. Conductors- Materials that allow electrons to flow freely from particle to particle. Examples are metals, graphite, and the human body.

Coulomb

The SI unit of electrical charge. One Coulomb (Symbol C) is equal in magnitude to the total charge of 6.25X10^18 electrons

Explain why and how you can affect resistance

This is the opposing of the flow of charges It depends on the thickness of the wire, the length of the wire, the conductivity of the material, and the temperature ex. as length increases so does resistance Measured in ohms - Ω

Explain overloading and how fuses and circuits work

When current gets too hot Fuses keep current at a safe level Circuits switch off the current flow

Direct current

an electrical current flowing in one direction only.

Compare and contrast AC and DC

direct current (dc)- flow of chargers in one direction alternating current (ac)- flow of charges in one direction and then in the opposite direction

Alternating current

electric current that repeatedly reverses its direction; the electrical charge vibrate about relatively fixed point. in the united states the vibrational rate of 60 Hz.

Explain why current occurs

flow of charged particles rate of electrical flow is measured in amperes (A) it is the rate of flow of 1 C of charge per second two types direct current (dc)- flow of chargers in one direction alternating current (ac)- flow of charges in one direction and then in the opposite direction usually alternate at a frequency of 60 cycles per second or 60 Hz Current= I, measured in A

Describe how objects become charged

how something is charge is an atom gains electrons, it has a negative charge but if an atom loses electrons it a positive charge

Electrically Polarized

term applied to an atom or molecule in which the charges are aligned so that one side a slight excess of negative charge.

Potential Difference

the difference in potential between two points, measured in volts and often called voltage difference.

Electric current

the flow of electric charge that transports energy from one place to another.

Coulombs Law

the relationship among electrical forces, charge, and distance:If the changes are alike in sign, the force is repelling; if the charges are unlike, the force is attractive

Ohm's Law

the statement that the current in a circuit varies in direct proportion to the potential difference or voltage and inversely with the resistance (CURRENT=VOLTAGE/RESISTANCE)

ampere

the unit of electrical current; the rate of flow of 1 C of charge per second.