Electric note 3 and 4

Current electricity

The continously flow of electrons in a circuit. Needs two things, an energy source(batteries,plugs), a full and completed circuit.

Energy source

Provides the electrons for the circuit

Conductor

Moves electrical currents in a circuit

Load

Converts electrical energy into another form or electricity

Switch

Not necessary, but most circuits will have a switch. Open=off, Closed=on

Electrochemical cells (batteries)

Batteries includes one electrolyte and two electrodes. Converts chemical energy into electrical energy that can be used in a circuit

Electrolyte

A liquid or paste that conducts electricity

Electrode

Metal strips that react with electrolytes

How lytes and trodes react

One trode becomes positive and the other becomes negative, which allows it to flow. Where a battery dies, the trodes wear away

Dry cell

When the electrolyte is a paste (aa or aaa batteries)

Wet cell

When the electrolyte is a liquid (car battery)

Potential energy

Energy that is stored in an object

3 things about pot. energy

Every electrons has electric pot energy.

Pot. energy is converted into different types of energy

Objects can have a high or low Pot. energy

Potential difference/Voltage

The difference between any 2 points in a circuit

How batteries flow into a circuit

A battery has a chemical pot. difference. The electrolytes react with the electrodes and create a difference of electrons on each electrode. The electrons are repelled from the negative end to the positive end. This causes a flow.

What do you measure voltage with

Voltmeter, must be hooked up by placing 2 probes on 2 points in circuit. In parallel

How electrons move in a circuit

Electrons all move together at the same speed, so when one moves, it pushes the on infront of it, like water in a hose.

Electric current

The amount of electric charge that passes a point every second. Must be a constant flow.

Two types of currents

Alternating current and direct current.

What do you measure current with

Ammeter, must be hooked up by putting it in a place where the current flows through (aka in series)

Resistance

How much a substance opposes the flow of electric current.

Substances and resistance

All substances resist currents, conductors have low, insulators have high.

What happens when a current slows down enough

The energy turns into a different energy like heat light sound and kinetic. This means you have more pot. energy before going into a load/resistors

What do you measure resistance with

Multimeter. Can be hooked in series or parallel.

3 units for voltage, current and resistance

Volts(V) , Amps(I), Ohms(Ω)

What is resistance affected by

Material, Temperature, length, diameter

Material

Silver has the least resistance, but copper is used because silver is too expensive

Temperature

A cold wire has low resistance, hot has it high. Cold has high current, hot has low. The particles bounce so much that the current gets lower in heat and they can’t push each other properly

Length + Diameter

The longer the wire the more resistance.

The thicker the wire, the less resistance.

Circuit diagrams

Drawings that use symbols

3 rules of circuit diagrams

1.Circuit diagrams are drawn as simply and neatly as possible

2.All corner must be 90 degrees, so wires are either vertical or horizontal.

3.Nothing can be drawn on corners, includes intersections but not junction points

Series circuit

One path for the electrons to flow. If the path is broken, it stops completey and becomes open.

Parallel circuit

2 or more paths for the electrons to flow. If only one of the paths are broken, other circuit will still work.

Series and voltages

Each load uses some of the total voltage that was supplied by the power source because all electrons must go through all loads.

Vt= V1+V2+V3…. Vn

Parallel and voltages

Each path uses all votage supplied by the power source because electrons can choose different paths.

Vt=V1=V2=V3…=Vn

Series and current

Current is the same throughout the circuit because electrons only have 1 path to take so everything moves the same speed

It=I1=I2=I3…=In

Currents and parallel

Current is shared between the different paths because electrons have 2 or more paths to moves

It=I1+I2+I3…+In

Resistances and series

Each load contributes some of the total resistance into the circuit. More loads means more resistance. This is all because electrons must go through every load

Rt= R1+R2+R3…Rn

Resistances and parallel

Each path contributes an inverse of the total resistance in the circuit. More loads means less resistance on different paths. This is because electrons can now choose different paths.

1÷Rt+ 1÷R1+ 1÷R2+ 1÷R3+…. 1÷Rn