Overview
This lecture explains the basic electrical terms volts, amps, ohms, and watts, and how they relate to circuits and power consumption.
Voltage (Volts)
- Voltage (V) is the electrical "pressure" that pushes charges through a circuit.
- It represents the difference in electric potential between two points.
- Voltage can be measured in AC (changes direction) or DC (constant direction).
- Typical voltage examples: 120V (US outlet), 240V (appliances), 7200V (power lines).
- In calculations, voltage is represented as V or sometimes E (electromotive force).
- Voltage is always measured between two points.
Current (Amps)
- Current (I) is the flow rate of electric charge through a circuit, measured in amperes (amps).
- Measured by seeing how much charge flows through a point per unit time.
- Amperage is measured in-line with the circuit, not across two points.
Resistance and Impedance (Ohms)
- Resistance (R) is the opposition to current in DC circuits, measured in ohms (Ω).
- Impedance is the total opposition to current in AC circuits, combining resistance and reactance.
- Reactance comes from circuit components like inductors and capacitors.
- Resistance slows current flow to safe and usable levels in circuits.
- More resistance means less current flows for the same voltage.
Power (Watts and VA)
- Wattage (W) measures electrical power, indicating energy consumed or expended (e.g., heat, light).
- Power is calculated as P = V × I (voltage times current).
- Volt-amps (VA) describe apparent power, often used for devices that store energy (e.g., transformers).
- Real power (watts) is for devices that convert electricity into light, heat, or work.
Key Terms & Definitions
- Voltage (V or E) — Electrical pressure or potential difference between two points.
- Current (I) — Flow rate of electric charge, measured in amperes (amps).
- Resistance (R) — Opposition to current flow in a circuit, measured in ohms (Ω).
- Impedance — Combined opposition (resistance + reactance) to AC current.
- Watt (W) — Unit of electrical power, amount of energy used or produced per second.
- Volt-amp (VA) — Apparent electrical power, often used for stored or transferred energy.
Action Items / Next Steps
- Practice measuring voltage, current, and resistance using a multimeter.
- Review the Ohm’s Law formula wheel and related calculations.
- Watch recommended videos on circuit diagrams and grounding for deeper understanding.