Electric current is the flow of electric charge. This guide covers what current is, how it's measured, and why it matters.
What is Electric Current?
Current is the movement of charge (often electrons) in a conductor. It is measured in amperes (A): 1 A = 1 coulomb/second.
Measuring Electric Current
Common units:
- Ampere (A) — SI base unit of electric current
- Milliampere (mA) — 0.001 A
- Microampere (μA) — 0.000001 A
- Kiloampere (kA) — 1,000 A
Types of Electric Current
Direct Current (DC)
Flows one way at constant rate. Sources: batteries, solar cells, DC supplies. Uses include electronics and EVs.
- Battery-powered devices
- Electronic circuits
- Electric vehicles
Alternating Current (AC)
Reverses direction periodically. This is household and grid power. Key traits:
- 50/60 Hz standard frequency
- Easy voltage transformation
- Efficient long-distance transmission
How is Electric Current Measured?
Use an ammeter (or multimeter). Steps:
- Turn off power
- Open circuit where measuring
- Insert meter in series
- Restore power and read
Safety Note
High currents are dangerous. Follow safety practices; consult a qualified electrician when unsure.
Common Applications of Electric Current
Residential
- Lighting systems
- Home appliances
- HVAC systems
- Entertainment electronics
Industrial
- Electric motors
- Manufacturing equipment
- Industrial heating
- Process control
Understanding Current Ratings
Devices have maximum current ratings; exceeding them risks overheating and damage. Examples:
- Household circuits: 15–20 A
- USB ports: 0.5 A (std) to 3 A (USB‑C PD)
- Smartphone chargers: 1–3 A
- EV charging: 16–32 A home; up to 500 A fast charging
Did You Know?
Humans can feel currents near 1 mA; >10 mA can cause muscle lockups.