Electric Current

• Electric current is a basic concept of electricity and describes the flow of electric charge through a conductor.
• In daily life, electric current is involved in the working of bulbs, fans, chargers, mobile devices, and household wiring.
• A steady electric current is observed in circuits where charges move continuously through a closed conducting path.

• The unit of electric current, ampere, is named after the French scientist André-Marie Ampère.
• Ampère carried out important experiments in electricity, and his work helped establish methods for understanding and measuring electric current.
• The visible source material includes this historical note as supporting background rather than as the main concept.

Current is defined as the rate of flow of charge.

A continuous and closed path of an electric current is called an electric circuit.

I = \[\frac {Q}{t}\]

Where:

• I = electric current
• Q = charge flowing through the conductor
• t = time taken

SI unit of current = ampere (A).

1. Explanation

• Electric current is produced when electric charges flow through a conductor.
• In metallic conductors, electrons are the charge carriers.
• Current exists only when there is a closed circuit.

2. Electric Circuit

• A circuit must be continuous and closed for current to flow.
• If the switch is open or the circuit is broken, current stops flowing, and electrical devices stop working.

3. Direction of Current

• Electrons move from the negative terminal to the positive terminal.
• By convention, current is taken to flow from the positive terminal to the negative terminal in the external circuit.
• Therefore, conventional current is opposite to electron flow.

4. Important facts

• Charge on one electron is approximately 1.6 × 10^-19 C.
• Small currents are expressed as: 1 mA = 10^-3 A and 1 μA = 10^-6 A.
• The source material also presents current as a useful quantity for describing charge flow in circuits and devices.

5. Quick process view

• Charge moves through a conductor.
• Movement occurs through a closed path called an electric circuit.
• The amount of charge passing per unit time gives the current.
• Current is measured in amperes.

Question: A charge of 30 C flows through a wire in 2 minutes. Find the current. 

Solution: Given, Q = 30 C
Time, t = 2 min = 120 s

Using I = \[\frac {Q}{t}\],

Answer: 0.25 A.

Question: A current of 0.5 A flows through a bulb for 10 minutes. Find the charge passed. 

Solution: Given, I = 0.5 A
Time, t = 10 min = 600 s

Using Q = It,

Answer: 300 C.

• Electric current is used in lighting devices such as bulbs and torches.
• Household appliances work only when current flows through a complete circuit.
• Very small currents are important in electronic circuits, sensors, and mobile devices.
• Lightning is also an example of a large-scale movement of electric charges mentioned in the source references.

• Electricity is a convenient and controllable form of energy widely used in homes, industries, schools, and hospitals.
• Electric current is produced when electric charges flow through a conductor, and it flows only through a closed, continuous electric circuit.
• A switch completes or breaks the circuit; when the circuit is broken, current stops flowing, and devices like bulbs do not glow.
• Electric current is the rate of flow of charge, given by the relation I = Q / t, where Q is charge and t is time.
• In metallic wires, electrons are the charge carriers, but by convention, current flows from the positive to the negative terminal, in the opposite direction to electron flow.