AC Electricity

What is Alternating Current???

1. Alternating current (AC) electricity is the type of electricity commonly used in homes and businesses throughout the world.

2. While direct current (DC) electricity flows in one direction through a wire, AC electricity alternates its direction in a back-and-forth motion.

3. The direction alternates between 50 and 60 times per second, depending on the electrical system of the country.

4. AC electricity is created by an AC electric generator, which determines the frequency.

5. What is special about AC electricity is that the voltage can be readily changed, thus making it more suitable for long-distance transmission than DC electricity.

Difference between AC and DC electricityElectrons move direct with DC electricityWith DC electricity, connecting a wire from the negative (−) terminal of a battery to the positive (+) terminal will cause the negative charged electrons to rush through the wire toward the positive charged side.

Electrons alternate directions in AC electricityWith an AC generator, a slightly different configuration alternates the push and pull of each generator terminal. Thus the electricity in the wire moves in one direction for a short while and then reverses its direction when the generator armature is in a different position.

Transforming voltagesAC voltages can be readily transformed to higher or lower voltage levels, while it is difficult to do that with DC voltages.High voltages are more efficient for sending electricity great distancesThis is because the high voltages from the power station can be easily reduced to a safer voltage for use in the house.

Tuning circuitsAC electricity also allows for the use of a capacitor and inductor within an electrical or electronic circuit. These devices can affect the way the alternating current passes through a circuit. They are only effective with AC electricity.

Advantages of AC electricity

Properties of Alternating CurrentFrequency. commonly measured in cycles per second (cycles/sec) units of Hertz It ranges from 5 to 60 HzPeriod. amount of time required to complete one cycle of the waveformmeasured in seconds/cycleAC power at 50 Hz will have a period of 1/50 = 0.02 seconds/cycleWavelength. Wavelength is very similar to period as discussed above, except that wavelength is measured in distance per cycle where period is measured in time per cycle.  Amplitude. how positive or negative the voltage is

Evenly Alternating CurrentsSinusoidal Currents

Evenly alternating sine wave currents50 HzGives 100 pulsesIt is produced from the mains by reducing the voltage to 60-80 V with a step down transformerUsually surged to cause rhythmical muscle contractionsIt relieves pain & oedema

AC Generator

A/C generator / Dynamo

Machine which produces alternating current from mechanical energyIt is based on the phenomenon of electromagnetic inductionWhenever amount of magnetic flux linked with the coil changes an EMF is induced in the coilThe direction of current is given by Fleming’s right hand rule.

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