The difference between direct current (DC) and alternating current (AC) lies primarily in the direction of the current flow. Direct current flows steadily in one direction with a constant polarity, such as from batteries or cells. In contrast, alternating current continuously changes direction, flowing back and forth as the voltage alternates between positive and negative, like the electricity supplied to homes from power plants.
Direct Current (DC)
- Flows in a single, constant direction.
- Has fixed positive and negative terminals.
- Produced by cells, batteries, solar panels, and some electronic devices.
- Voltage typically remains steady.
- Commonly used in portable electronics and battery charging.
Alternating Current (AC)
- Continuously reverses direction, changing polarity periodically.
- Has two identical terminals with polarity that switches.
- Produced by electrical generators and mains electricity.
- Frequency is the number of direction changes per second; e.g., 50 Hz in the UK.
- Efficient for long-distance transmission and used in domestic and industrial power supply.
Summary Table
Feature| Direct Current (DC)| Alternating Current (AC)
---|---|---
Direction of current| One constant direction| Changes direction periodically
Polarity| Fixed positive and negative terminals| Polarity switches back and
forth
Common sources| Batteries, cells, solar panels| Electrical generators, mains
electricity
Voltage| Usually constant| Varies periodically
Typical uses| Electronic devices, battery charging| Household and industrial
power supply
Transmission| Less efficient for long distances| More efficient for long-
distance transmission
Frequency| None| Frequency measured in hertz (cycles per second)
This fundamental difference affects how each type of current is used and generated in electrical systems.
