What is the difference between AC and DC current?

Direct Current (DC) flows continuously in one direction (produced by batteries). Alternating Current (AC) periodically reverses its direction of flow (supplied by power grids/wall outlets).

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Core Study Guide

Electric Circuits

The physics of charge flow, resistance, and electrical energy.

Electric current is the rate of flow of charge. Circuits direct this flow through pathways of conductors, resistors, and energy sources.

This unit covers Ohm's Law, equivalent resistance in series and parallel networks, Kirchhoff's laws, and electrical power dissipation.

Key Takeaways

•Ohm's Law states that current is directly proportional to voltage and inversely proportional to resistance.
•Equivalent resistance increases in series circuits but decreases in parallel networks.
•Kirchhoff's Junction Law states that total current entering a node must equal current leaving it.

Core Concepts & Definitions

1Ohm's Law

V = I * R. Current (I) increases with voltage (V) but decreases with resistance (R).

•Ohmic materials maintain constant resistance under temperature changes.

•Non-ohmic components (like diodes) have non-linear I-V curves.

2Series and Parallel Networks

Resistors can be configured in two main layouts.

•Series: Rs = R1 + R2 + R3. Current remains identical throughout.

•Parallel: 1/Rp = 1/R1 + 1/R2 + 1/R3. Voltage remains identical across branches.

Quick Revision Notes

•Ammeters measure current and must be connected in series; voltmeters measure potential difference and must be connected in parallel.
•Kirchhoff's Junction Law represents conservation of charge.