# Electrical Current - PowerPoint PPT Presentation

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Electrical Current. I. What is Electrical Current?. Definition The rate at which charges pass a given point Units of measurement Amperes Shortened to Amps 2 Types of Current DC AKA: direct current Electrons always flow in the same direction.

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Electrical Current

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## Electrical Current

### I. What is Electrical Current?

• Definition

• The rate at which charges pass a given point

• Units of measurement

• Amperes

• Shortened to Amps

• 2 Types of Current

• DC

• AKA: direct current

• Electrons always flow in the same direction.

• Batteries in a camera or a flashlight use DC

• AC

• AKA: alternating current

• The electrons can move in either direction

• Electrical outlets in your home use this.

### II. Voltage

• Definition

• The measure of how much work is needed to move a charge between 2 points.

• Units of measurement

• Volts (V)

• Relationship between voltage and current

• As long as there is voltage between 2 points on a wire, charges will flow in the wire.

• The greater the voltage:

• The greater the current.

• Different batteries have different voltages

• Car batteries need a bigger current to start the car so they have a higher voltage.

9 Volts

1.5 Volts

6 Volts

### III. Resistance

• Definition

• The opposition to the flow of electric charge

• Like “electrical friction”

• Units of Measurement

• Ohm’s

• Represented by the Greek letter omega ( )

• Variables which affect resistance

• Material

• Good conductors have a:

• Low resistance

• Like Copper

• Insulators have a:

• High resistance

• Temperature

• As you increase a metals temperature

• You increase resistance

• Superconductors

• Metals at very low temperature who’s resistance is virtually 0

### IV. Electrical “Cells”

• Definition:

• These change chemical or radiant energy into electrical energy

• Parts

• Electrolytes

• Mixture of chemicals which allow charges to flow

• Electrodes

• Points at which charges enter and leave the cell.

• 2 Types

• Dry Cell

• Electrolytes are solid or paste

• Normal batteries

• Wet Cell

• Electrolytes are liquid

• Car batteries

### V. Electrical Calculations

• Ohm’s Law

• Relates current, voltage, and resistance

• Voltage = Current X Resistance

• V = I X R

• Electrical Power

• Power = Voltage X Current

• P = V X I

• Measured in Watts