Introduction to Current Electricity

Current electricity is… a flow of electrons around a circuit.

I. Voltage acts like a force A. Voltage causes electrical I. Voltage acts like a force A. Voltage causes electrical charge (electrons) to move through an electrical circuit.

I. Voltage acts like a force B. A voltage source pushes I. Voltage acts like a force B. A voltage source pushes electrons into a circuit, which knocks electrons loose from the atoms in the conductor.

I. Voltage acts like a force C. The loose electrons carry the I. Voltage acts like a force C. The loose electrons carry the charge to the load which converts the electricity into another form of energy.

I. Voltage acts like a force Like a bucket brigade, the circuit doesn’t work if it is broken or open.

II. Components of a circuit:. A. Voltage sources are II. Components of a circuit: A. Voltage sources are batteries or generators.

II. Components: B. Control elements are devices that change the flow of electricity - power switch - volume control on a radio - dimmer switch

II. Components: C. A load is a device that uses. electricity. - motor II. Components: C. A load is a device that uses electricity. - motor - bulb - heater

II. Components:. D. A conductor is a material. that allows movement of II. Components: D. A conductor is a material that allows movement of electrical energy

III. Types of Current. A. Direct current (DC) happens III. Types of Current A. Direct current (DC) happens when the electric current flows in one direction only. 1. Batteries produce DC by chemical reactions.

a. Batteries have two electrodes. or terminals that connect to a a. Batteries have two electrodes or terminals that connect to a circuit. When we connect a battery to a circuit, a chemical reaction begins and charges (electrons) flow from the negative terminal to the positive terminal. (negative) (positive)

Alternating current (AC) is. electric current that changes .Alternating current (AC) is electric current that changes direction rapidly. 1. The rate of change is called frequency. a. Frequency is measured in cycles per second or hertz (Hz).

2. AC is produced by generators. Generators use a coil of wire 2. AC is produced by generators. Generators use a coil of wire moving in a magnetic field to force electric charges to move.

In North America, AC cycles at 60 hertz In North America, AC cycles at 60 hertz. The voltage delivered to most homes is 110 - 120 volts. The electricity in our homes is rated at 120 V AC, 60 Hz.

In North America, AC cycles at 60 Hz. In Europe, AC cycles at 50 Hz.

IV. Measuring electricity A. The unit for charge is the coulomb (C). 1. One coulomb = 6.24 x 1018 electrons Because an electron is so tiny, we refer to groups of them (coulombs). Imagine having to discuss the number of grains of sand in a truckload of sand. Which is easier? “I’d like you to deliver 6.24 x 1018 grains of sand to my house.” or “I need a truckload of sand.”

IV. Measuring electricity B. Current is the amount of charge IV. Measuring electricity B. Current is the amount of charge that passes a point in one second. 1. The unit for current is the ampere or amp (A). 2. 1 amp = 1 Coulomb/sec 3. Current in a circuit is measured with an ammeter.

Measuring electricity C. Voltage is potential difference, Measuring electricity C. Voltage is potential difference, the push that moves charges through a circuit. 1. The unit for voltage is the volt (V). 2. Voltage differences in a circuit are measured with a voltmeter.

IV. Measuring electricity D. Electrical power is the rate at IV. Measuring electricity D. Electrical power is the rate at which energy is transformed. 1. Electric power = current x voltage. 2. The unit for power is the watt (W). 1 watt = 1 amp x 1 volt

IV. Measuring electricity E. Resistance is the opposition to IV. Measuring electricity E. Resistance is the opposition to the movement of electricity. The unit for resistance is the ohm ().

Measuring electricity F. Symbols you will see:. q. =. charge Measuring electricity F. Symbols you will see: q = charge (in coulombs) I = current (in amps or C/sec) V or E = voltage (in volts) R = resistance (in ohms or )

Notes on measuring electricity: - Notes on measuring electricity: - For any device, it is important to use the proper settings. Failure to do this may result in permanent damage to the device. - Anytime we work with electricity, failure to follow directions may result in permanent damage to YOU or your classmates.