Topic: Power Delivery, DC Circuits, and Ohm’s Law

Essential Question:

How do voltage, current, and resistance interact in a DC circuit, and how do technicians apply Ohm’s Law to diagnose power failures?

Focus Notes (Students Copy)

Voltage (V): the electrical pressure pushing electrons.

Current (I): flow rate of electrons, measured in amps.

Resistance (R): opposition to current; measured in ohms (Ω).

Ohm’s Law:

• V = I × R
• I = V ÷ R
• R = V ÷ I

DC (Direct Current): one-way electron flow; used in all computers, laptops, Chromebooks.

Wire Gauge:

• lower gauge = thicker wire = less resistance
• higher gauge = thinner wire = more resistance

Technician Application:

• If a device powers off under load → insufficient current
• If a device charges slowly → high resistance / bad cable
• If voltage drops at a connector → failing adapter or damaged wire

Practice