Electric Current
Understanding electric current, its types, and how it is measured.
What is Electric Current?
Electric current is the rate of flow of electric charge. It is the movement of charged particles, typically electrons, through a conductor or space. The SI unit of electric current is the Ampere (A).
Types of Electric Current
- Direct Current (DC): Current that flows in only one direction. Examples include batteries and solar cells.
- Alternating Current (AC): Current that periodically reverses direction. This is the type of current supplied to homes and businesses by power grids.
Measuring Electric Current
Electric current is measured using an ammeter, which must be connected in series with the circuit component through which the current is to be measured.
Relationship with Voltage and Resistance (Ohm's Law)
I = V / R
Where:
• I = Current in Amperes (A)
• V = Voltage in Volts (V)
• R = Resistance in Ohms (Ω)
Where:
• I = Current in Amperes (A)
• V = Voltage in Volts (V)
• R = Resistance in Ohms (Ω)
Typical Current Values
| Device/Application | Approximate Current (A) |
|---|---|
| LED (small) | 0.01 - 0.02 |
| Smartphone Charger | 1 - 3 |
| Hair Dryer | 10 - 15 |
| Electric Kettle | 10 - 15 |
| Main Household Circuit Breaker | 15 - 200 |
Frequently Asked Questions
What is the direction of conventional current?
Conventional current is defined as the direction in which positive charges would flow. This is opposite to the actual flow of electrons, which are negatively charged.
How does current relate to charge and time?
Current (I) is the rate of flow of charge (Q) over time (t): I = Q / t. One Ampere is equal to one Coulomb of charge flowing per second.