CLASS VII- INTRODUCTION TO ALTERNATING CURRENT AND DIRECT CURRENT

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What is AC & DC?


Alternating current

u  Obtained from power plant, AC generator

u  Current reverse its direction. Current is not unidirectional.

u  Frequency of AC is 50Hz (in India) or 60Hz depends on country.

u  Flow of electron keep switching direction- forward or backward.

u  Safe to transfer over longer city distances and can provide more power.

Direct current

u  Obtained from battery, fuel cell, solar cell.

u  Current always flow from positive to negative terminal of battery.

u  Frequency of DC is zero.

u  Flow of electron steadily in one direction.

u  Voltage of DC can not travel very far until it begins to lose energy.

 

 

What is the frequency of alternating current in India ?

( 50 Hz)

 

u  AC can even be changed to DC by an adapter that you might use to power the battery on your laptop.

u  Rectifier is used to convert AC into DC.

u  Inverter is used to convert DC into AC.

u  For example, for your car an inverter would change 12V DC to 120V AC to run a small device.

u  DC can be stored in batteries but AC can not be stored.

 

 

Another difference between AC & DC involves the amount of energy it can carry. Each battery is designed to produce only one voltage, and that voltage of DC can travel very far until it begins to lose energy. But ac voltage from a generator, in a power plant, can be bumped up or down in strength by TRANSFORMER . Transformer are located on the electrical pole on the street. They change very high voltage into a lower voltage, which is appropriate for your home appliances, like lamp, refrigerator.

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