Types of Current

Electric current is the flow of electric charge in a circuit. Based on the nature of this flow, current is classified into Direct Current (DC) and Alternating Current (AC).

• DC flows in a single direction and has a constant voltage.
• It is non-oscillatory, meaning it does not change its direction over time.
• It can increase, remain stable, or decrease over time but does not alternate.

Sources of DC:

• Batteries
• Solar cells
• Fuel cells
• DC generators

Uses of DC:

• Mobile phones, flashlights, laptops
• Electric vehicles
• Electronic devices

Graphical Representation of DC:

• A straight line in a graph represents steady DC.
• A sloped or stepped line represents increasing or decreasing DC.

AC current and DC current

Alternating current and Direct current (Graphical)

• Alternating Current (AC) changes its direction and magnitude periodically over time.
• It follows a sinusoidal waveform, moving forward and backward at equal time intervals.
• The number of cycles per second is measured in Hertz (Hz).
• In India, AC frequency is 50 Hz (i.e., 50 cycles per second).
• AC is preferred for power transmission over long distances due to minimal power loss.

Sources of AC:

• Power plants (electricity generation stations)
• Alternators and dynamos
• AC generators

Uses of AC:

• Home electricity supply
• Refrigerators, washing machines, televisions
• Large industries and power stations

Graphical Representation of AC:

• AC follows a sinusoidal wave (S-shaped curve).
• The current moves above and below the zero line, indicating periodic change in direction.