Chapters 10-11 Physical Science

Electromagnet

Electromagnet

a magnet whose field is produced by an electric current - electromagnets are usually in the form of a wire coil with a piece of iron inside the coil

Electromagnetic induction

a magnetic field is induced in any region of space in which an electric field is changing with time - the magnitude of the induced magnetic field is proportional to the rate at which the electric field changes

faraday’s law

the induction of voltage when a magnetic field changes with time - if the magnetic field within a closed loop changes in any way, a voltage is induced in the loop

generator

an electromagnetic induction device that produces electric current by rotating a coil within a stationary magnetic field - a generator converts mechanical energy to electrical energy

magnetic domains

clustered regions of aligned magnetic atoms - when these regions are aligned with one another, the substance containing them is a magnet

magnetic field

the region of magnetic influence around either a magnetic pole or a moving charged particle

magnetic force

1) between magents, it is the attraction of unlike magnetic poles for each other and the repulsion between like magnetic poles

2) between a magnetic field and a moving charged particle, it is a deflecting force due to the motion of the particle - it is perpendicular to the velocity of the particle and perpendicular to the magnetic field lines - also, it is greatest when the particle moves perpendicular to the field lines and zero when the particle moves parallel to the field lines

maxwell’s counterpart to faraday’s law

an electric field is induced in any region of space in which a magnetic field is changing with time. the magnitude of the induced electric field is proportional to the rate at which the magnetic field changes

motor

a device employing a current-carrying coil that is forced to rotate in a magnetic field - a motor converts electrical energy to mechanical energy

Alternating Current

electrically charged particles that repeatedly reverse direction, vibrating about relatively fixed positions

Ampere

unit of electric current, equivalent to 1 Coulomb per second

Coulomb

the unit of electrical charge - it is equal in magnitude to the total charge of 6.25 × 10 ^18 electrons

Coulomb’s Law

The electrical force between two charged bodies is directly proportional to the product of the charges and inversely proportional to the square of the distance between them

Direct Current

electrically charged particles flowing in one direction only between them

Electric Current

the flow of electric charge that transports energuu from one place to another - measured in amperes

Electrically Polarized

term applied to an atom or molecule in which the charges are aligned so that one site has a slight excess of positive charge and the other side a slight excess of negative charge

Electric Power

the rate of energy, or rate of doing work - measured by power = current x voltage

Electrical Resistance

the property of a material that resists the flow of charged particles through it - measured in ohms

Ohm’s Law

the statement that the current in a circuit varies in direct proportion to the voltage across the circuit and inversely with the circuit’s resistance - current = voltage / resistance

Parallel Circuit

an electric circuit in which electrical devices are connected so that the same voltage acts across each one and any single one completes the circuit independently of all the others

Series Circuit

an electric circuit in which electrical devices are connected so that the same electric current exsists in all of them

Voltage

a form of “electrical pressure” - voltage = potential energy/ charge

What is the Law of Conservation of Change?

charge cannot be created nor destroyed (think Conservation of energy/momentum/etc.)

How does a person get shocked?

when there is a difference in voltage between one part of your body and another part

How is an electron current similar to a water current? How are the two different?

Sim: pipes carry water/wires carry electrons - it can move easy in a conducting material

Diff: electric current can flow through insulators

In which direction do electric currents flow?

the direction in which a postive charge would move

Basic structure of an atom

protons, neutrons, electrons

What are the two basic rules for electricity?

1. like charges repel each other

2. opposite charges attract each other

What is overloading? How can you prevent it?

carrying more than it can handle - hazards

prevent - fuses, surge protectors, etc.