Electric Circuits

Definition

An Electric Circuit is any complete path along which charge (electrons) can flow.

Why It Matters

Circuits are the fundamental transport systems for electrical power and signals in all electronic devices, from household appliances to computer microchips.

Core Concepts

• Current ($I$): The flow of electric charge. Measured in Amperes (A). $1 \text{ A} = 1 \text{ C/s}$.
  • How to read: “The current of one ampere equals one coulomb per second.”
  • Meaning: Rate of charge flow through a conductor—how much charge passes a point each second.
• Resistance ($R$): The property of a material to resist charge flow. Measured in Ohms ($\Omega$).
• Ohm’s Law: $I = \frac{V}{R}$
  • How to read: “The current I equals the voltage V divided by the resistance R.”
  • Meaning / when to use: Current is proportional to voltage and inversely proportional to resistance—the core relation for analyzing circuits.
• Electric Power ($P$): The rate at which energy is converted. $P = IV$
  • How to read: “The power P equals the current I times the voltage V.”
  • Meaning: Power delivered to a circuit element—product of current flow and electrical pressure.
• Circuit Types:
  • Series: A single path. If one device fails, all fail. Total resistance increases with more devices.
  • Parallel: Multiple branches. Devices operate independently. Total resistance decreases with more branches.

Connected Concepts

• Electric Potential
• Electric Charge
• Coulomb’s Law
• Magnetism
• Electromagnetic Induction
• Work
• Power