Electric current is one of the greatest discoveries that has made our lives easier. People have always been curious about lightning and how it forms. Even in ancient times, the Greeks studied magnetism and tried to understand electricity.
The journey of electricity and current has developed over time. It started with Benjamin Franklin’s kite experiment and later led to Michael Faraday’s invention of the electric generator in 1831. However, progress was slow because information took a long time to spread between countries. Many scientists worked on similar discoveries without knowing others had already made progress.
In this article, we will explore electric current, its properties, different types, and the effects it causes in our daily lives.
What is Electric Current?
Electric current is the flow of electric charges through a conductor. Before the discovery of electrons, scientists believed that current was the movement of positive charges. However, we now know that electric current is caused by the movement of negative charges (electrons).
Direction of Electric Current vs. Electron Flow
- Conventional Current Flow: Moves from the positive terminal to the negative terminal (higher to lower potential).
- Electron Flow: Moves from the negative terminal to the positive terminal (lower to higher potential).
Even though electrons move in the opposite direction, we still follow the conventional current flow in circuit diagrams and electrical calculations.
Key Takeaways
✔ Electric current is the movement of electrons in a conductor.
✔ Conventional current flows from positive to negative, while electrons flow from negative to positive.
✔ Understanding electric current is essential for circuit design, electronics, and electrical engineering.
What is the Formula for Electric Current?
Electric current (I) is defined as the rate of flow of electric charge (q) over time (t). It is mathematically expressed as:
I=q / t
Where:
- I = Electric current (measured in Amperes, A)
- q = Electric charge (measured in Coulombs, C)
- t = Time (measured in seconds, s)
Understanding the Formula
- Electric charge (q) is a fundamental quantity like mass or length.
- The unit of charge is the Coulomb (C), and when 1 Coulomb of charge flows per second, the current is 1 Ampere.
- The SI unit of electric current is Ampere (A), which is equivalent to 1 Coulomb per second (C/s).
Key Takeaways
✔ Electric current measures the flow of electric charge over time.
✔ 1 Ampere = 1 Coulomb per second.
✔ The formula I = q/t is essential for circuit analysis, physics problems, and electrical engineering.
Properties of Electric Current
Electric current is a fundamental concept in physics and electrical engineering. Below are some essential properties of electric current that help us understand its behavior in circuits.
1. Electron Flow causes Electric Current
- Electric current is generated due to the movement of electrons in a closed circuit.
- In a metallic conductor, free electrons move and create a flow of charge.
2. Types of Electric Current: AC and DC
- Direct Current (DC): Flows in one direction and is used in low-voltage applications, such as batteries, aviation, and electronic circuits.
- Alternating Current (AC): Reverses direction periodically and is used in household electrical appliances, power grids, and industrial equipment.
3. Resistance Controls the Flow of Current
- By adding resistance to a circuit, the flow of current can be regulated or limited.
- Resistors and other components help protect devices from excessive current flow.
4. Electric Current is Measured in Amperes (A)
- The SI unit of electric current is the Ampere (A).
- 1 Ampere is equal to 1 Coulomb of charge moving per second: 1A=1C/s
5. Direction of Electric Current Flow
- Conventional Current Flow: Moves from higher electric potential (+ terminal) to lower electric potential (- terminal).
- Electron Flow: Moves in the opposite direction, from negative to positive terminal.
Key Takeaways
✔ Electric current is the movement of electrons in a conductor.
✔ It exists in two forms: Direct Current (DC) and Alternating Current (AC).
✔ Resistance is used to control current flow in a circuit.
✔ Current is measured in Amperes (A), where 1A = 1C/s.
✔ The conventional current direction is from positive to negative.
Types of Electric Current
Electric current is categorized into two main types based on its flow direction and behavior over time:
1. Direct Current (DC)
✔ Definition: Direct Current (DC) flows in one constant direction without changing over time.
✔ Electron Movement: Free electrons move from the negative terminal to the positive terminal in a DC circuit.
✔ Conventional Current Flow: Since current was originally defined as the movement of positive charges, the conventional direction of current is opposite to electron flow.
✔ Applications of DC:
- Batteries (e.g., mobile phones, laptops, cars)
- Solar panels
- Low-voltage electronic devices (e.g., LED lights, aviation systems)
2. Alternating Current (AC)
✔ Definition: Alternating Current (AC) changes direction periodically, meaning the flow of electric charge reverses multiple times per second.
✔ Electron Movement: Electrons move back and forth, switching direction continuously.
✔ Frequency: The number of times AC changes direction per second is called its frequency, measured in Hertz (Hz). For example:
- In India & Europe: 50 Hz (AC reverses 50 times per second)
- In the USA: 60 Hz
✔ Applications of AC:
- Household electricity supply
- Power grids & transformers
- Large appliances (e.g., refrigerators, washing machines, air conditioners)
Key Differences Between AC and DC
| Feature | Direct Current (DC) | Alternating Current (AC) |
|---|---|---|
| Direction | Flows in one direction | Changes direction periodically |
| Electron Flow | Moves from negative to positive | Moves back and forth |
| Frequency | 0 Hz (constant flow) | 50 Hz or 60 Hz (depending on the region) |
| Power Supply | Batteries, solar panels | Power grids, home appliances |
| Best for | Low-voltage electronics | Long-distance power transmission |
Key Takeaways
✔ DC current flows in a single direction, while AC current changes direction periodically.
✔ AC is used for power transmission, while DC is used in batteries and electronics.
✔ The frequency of AC varies by region (50 Hz in India & Europe, 60 Hz in the USA).
✔ Understanding AC and DC helps in choosing the right power source for different applications.
Effects of Electric Current
Electric current produces various effects when it flows through a conductor. The three main effects of electric current are:
- Heating Effect
- Magnetic Effect
- Chemical Effect
1. Heating Effect of Electric Current
When an electric current flows through a conductor, it faces resistance, which converts some of the electrical energy into heat energy. This phenomenon is called the Joule heating effect or heating effect of electric current.
Formula for Heat Generation
H=I2Rt
Where:
- H = Heat energy (Joules)
- I = Electric current (Amperes)
- R = Resistance of the conductor (Ohms)
- t = Time for which current flows (Seconds)
Key Observations
✔ Higher resistance produces more heat.
✔ More current flow results in greater heat generation.
✔ Heat is used in devices like electric irons, water heaters, and toasters.
✔ Even connecting wires get slightly warm due to small resistance.
2. Magnetic Effect of Electric Current
When an electric current flows through a conductor, it generates a magnetic field around it. This is known as the magnetic effect of electric current.
Key Concepts
✔ Moving electric charges create a magnetic field around them.
✔ This effect is the principle behind electromagnets and devices like electric bells, motors, and transformers.
✔ Example: When electricity flows through a wire, a compass needle placed nearby deflects, proving the presence of a magnetic field.
Applications
- Electromagnets (used in cranes for lifting heavy metal objects)
- Electric motors (used in fans, washing machines, etc.)
- Magnetic relays and electric bells
3. Chemical Effect of Electric Current
When an electric current passes through a liquid (especially an electrolyte), it breaks down into ions, causing chemical changes. This is called the chemical effect of electric current.
Electrolysis Process
✔ The process of passing electricity through a solution to cause a chemical reaction is called electrolysis.
✔ The outcome depends on the type of electrodes and the composition of the solution.
Key Observations
✔ Color change in the solution
✔ Metal deposition on electrodes
✔ Formation of gas bubbles at the electrodes
Applications
- Electroplating (coating metals like gold or silver on jewelry)
- Purification of metals (such as copper)
- Production of hydrogen gas in industries
Key Takeaways
✔ Electric current produces heating, magnetic, and chemical effects.
✔ The heating effect is used in appliances like toasters, heaters, and irons.
✔ The magnetic effect is used in motors, electromagnets, and electric bells.
✔ The chemical effect is used in electroplating, battery charging, and purification of metals.
