ELECTRIC CURRENTP. 516-518

A battery is a device that converts stored chemical potential energy into electrical energy and is capable of providing a steady flow of current electricity.

Current electricity is the flow of charged particles along a conductor.

Circuit Fundamentals

electrical circuit - steady flow of charged particles along a closed loop.

A circuit contains:a source of electrical energy, such as a

batterya conductor, such as a wirea load that changes electrical energy

into light, sound, heat, or motion. (can have a switch but doesn’t have to

have one for circuit to work)

Circuit symbols

Current

The amount of charge transferred per unit time is referred to as current.

When scientists first began studying circuits, they assumed that positive charges flowed through the wires in a circuit .

They called the flow of positive charges in a circuit conventional current.

Since unlike charges attract, conventional current is considered to flow from the positive terminal of a battery, around the circuit to the negative terminal.

Incorrect conventional current…

Correct electron flow…After scientists learned more about the

structure of atoms, they concluded that current consists of free electrons, which are negatively charged.

During the operation of a circuit, the electrons move from the negative terminal of the battery to the positive terminal.

The movement of electrons in a circuit is called electron flow.

we will stay with the convention and use the term conventional current.

What is current?

http://education-portal.com/academy/lesson/what-is-electric-current-definition-unit-types.html

TVOhttp://www.youtube.com/watch?v=YL

eRbTlKkJY

Current is represented by the symbol capital I, and is measured in amperes (A).

Q

Q

Volts or Amps….

http://www.youtube.com/watch?v=9iKD7vuq-rY

Direct Current (DC)

A battery provides a steady flow of current in one direction, known as direct current, or DC.

Strictly speaking, DC can fluctuate, but cannot change directions.

DC is used in all electrical equipment that requires an adapter when you plug it into a wall outlet or is powered by a battery.

Direct Current

The movement of electrons in only one direction, protons do not move

Alternating Current (AC)

A wall socket provides alternating current.Alternating current, or AC, changes

direction periodically. That is, the charges in the wire move back

and forth over the same spot and do not actually move from one terminal to another.

This type of current is used in the wiring of your house.

http://www.pbs.org/wgbh/amex/edison/sfeature/acdc.html

AC vs DC

http://www.youtube.com/watch?v=g17f9J1-r-k

http://www.youtube.com/watch?v=xyQfrzBfnDU

Sample problem 1

A battery delivers a charge of 9.00 C in 1.00 min of operation.

What amount of current is generated in mA? Q

Q

Measuring Current

A device called an ammeter is used to measure current.

The ammeter is placed into the circuit (series) so that the current flows through it.

Since the current cannot bypass the meter, the meter measures the entire current.

Sample Problem (p. 516)

Calculate the amount of current through a wire that has 0.85C of electrons passing a point in 2.5 min.

Given: Q= t= Required: I=? (A) Analysis: convert time to seconds,

solve for I

Homework

P. 517 practice #1-2P. 518 questions #1-4http://www.youtube.com/watch?v=1

xPjES-sHwg&feature=youtu.be