This document discusses alternating current (AC) and how it is generated, transmitted, and used. It explains that in an AC generator, the direction of the output current reverses each time the coil passes the vertical position. Transformers are used to increase or decrease AC voltages by using two coils with a different number of turns. Common devices like homes, offices, and large appliances use AC power from the electric grid, while devices like flashlights and laptops run on direct current from batteries.

2. • Current that flow into opposite direction alternately.
• This means that the direction of current flowing in a circuit is
constantly being reversed back and forth.
• In an AC generator, every time the coil passes the
vertical/upright position, the direction of the output current
reverses.
• The current obtained from the generator is Alternating
Current.

3. • At high voltages like as over 110kV, less energy is lost in
electrical power transmission. Higher voltages mean lower
currents, and lower currents mean less heat generated in the
power line due to resistance.
• AC can be converted from high voltages easily using
transformers.

4. • Transformer is a device that increase or decrease the
alternating voltage in electrical power applications.
• It transfers electrical energy between two or more circuits
through electromagnetic induction.

5. • An electric current (a flow of electric charge) has an
associated magnetic field/flux regardless of the material (or
space) the flow occurs in. This is a fundamental truth of
nature in electromagnism.
• The coil A is used to induce changing magnetic flux in soft
iron core.
• This in turn, induces an electric current in the coil B.
• If coil A has more turns than coil B, the voltage will be
decreased (step-down transformer).
• If coil A has less turns than coil B, the voltage will be
increased (step-up transformer).
N
N
V
V
p
s
p
s

Secondary Voltage
Primary Voltage
Secondary Turns
Primary Turns
=

6. • Home and office outlets are almost always used in AC.
• AC is also capable of powering electric motors.
• Useful for many large appliances like
refrigerators,dishwashers, and so on, which run on AC.
• The power grid:

8. • Direct current (DC) is a current which flows in one direction
only. All batteries produce direct current. This means that
there is no change of magnitude of the current.
• In other word, it is also called steady direct current
voltage source

9. Examples of devices that use DC:
• Flashlights
• Cell phones
• Laptops

11. GND +5V