Course 1 · Module 1 · 35 minutes
What electricity is actually doing
Voltage, current, resistance, power, and the circuit behavior behind familiar field work.
Learning objectives
Build the foundation.
- Distinguish voltage, current, resistance, and power
- Apply Ohm's Law and Watt's Law to residential loads
- Explain open circuits, short circuits, and ground faults
Section 1 of 4
Electricity needs a complete path
A useful circuit has a source, a conductive path, and a load. Current can flow only when that path returns to its source. This simple model will support every system you study later.
Keep these ideas
- The source establishes electrical potential difference.
- A closed path lets current travel through the load and return to the source.
- An open stops normal current; a short creates an unintended low-impedance path.
Source, pathway, load, and return
A labeled circuit that changes from open to closed and then highlights the normal current path.
Production brief
Create: Create a clean two-state diagram of a 120 V source, two conductors, a switch, and a lamp. Use amber arrows only in the closed state. Add a third inset showing an unintended line-to-neutral short.
Accessibility: Supply alt text that names every component and describes how the highlighted path changes.
Why the return path matters
Demonstrate a complete circuit, an open circuit, and a short circuit using a safe low-voltage trainer.
Production brief
Create: 5–7 minutes. Start with the completed circuit, open the switch, then demonstrate a protected short. Overlay the words source, path, load, and return as each part is discussed.
Accessibility: Provide edited captions, a transcript, and spoken descriptions of meter readings and visual changes.
Section 2 of 4
Voltage, current, and resistance
Voltage is electrical potential difference, current is the rate of charge flow, and resistance opposes that flow. Ohm’s Law describes how the three quantities change together.
Keep these ideas
- Voltage is measured in volts, current in amperes, and resistance in ohms.
- Ohm’s Law can be written E = I × R, I = E ÷ R, or R = E ÷ I.
- At constant voltage, decreasing resistance increases current.
One relationship, three forms
A reference graphic connecting volts, amperes, and ohms without relying only on the familiar triangle mnemonic.
Production brief
Create: Show the three equation forms beside one example circuit. Include units under every value and visually connect each measurement to the point where a meter would be placed.
Accessibility: Alt text must state all three equations and describe correct meter placement.
Watch resistance change current
Measure current through two resistive loads while keeping the source voltage constant.
Production brief
Create: 7–10 minutes. Use a low-voltage supply and two clearly labeled resistors. Predict each reading, calculate it on screen, then verify it with a meter.
Accessibility: Narrate every calculation and meter value; provide captions and a transcript with equations in plain text.
Section 3 of 4
Power and familiar loads
Power is the rate at which electrical energy is converted or used. Comparing watts and amperes turns abstract theory into practical decisions about real loads and branch circuits.
Keep these ideas
- Power is measured in watts and commonly calculated with P = E × I.
- At the same voltage, a higher-wattage load draws more current.
- A 1,500 W heater at 120 V draws 12.5 A.
From nameplate watts to circuit amperes
Compare a lamp, portable heater, and small motor at 120 V with their calculated current draw.
Production brief
Create: Create three side-by-side load cards. Show nameplate watts, the P ÷ E calculation, and resulting amperes. Keep values realistic and label motor values as simplified examples.
Accessibility: Alt text should list each load, wattage, voltage, and calculated current.
Read a load, calculate its current
Use appliance nameplates to predict and then measure current draw.
Production brief
Create: 6–8 minutes. Feature at least three loads, including a 1,500 W heater. Show the formula before energizing each load and compare calculated versus measured current.
Accessibility: Include close-up nameplate stills, spoken readings, captions, and a transcript.
Section 4 of 4
AC, DC, series, and parallel
Batteries provide familiar direct current, while dwelling systems use alternating current. Residential loads are arranged in parallel so each receives the intended voltage and operates independently.
Keep these ideas
- DC maintains one polarity; AC periodically reverses polarity.
- Series components share one current path.
- Parallel branches share the source voltage and can operate independently.
Direction and polarity over time
A synchronized comparison of a steady DC level and a 60 Hz AC waveform.
Production brief
Create: Use two aligned timelines. Label polarity, zero crossings, and one full cycle. Avoid implying that household energy pauses in a way that confuses RMS voltage.
Accessibility: Describe the DC line and the repeating positive/negative AC waveform in text.
Why homes use parallel circuits
Compare two lamps in series and in parallel, then open one lamp in each arrangement.
Production brief
Create: 7–9 minutes using a safe trainer. Measure voltage at both lamps, compare brightness, and show what happens when one lamp is removed.
Accessibility: Narrate brightness and meter changes instead of relying on visuals alone; provide captions and transcript.
Final step
Module assessment
Bring the four major ideas together. You can retry as often as needed; your best score is stored only on this device.
Before you begin
Complete all four sections.
The assessment remains available for practice, but module completion requires every section and a passing score.