Updated: Dec 9, 2025 | Source: 2022-2026 Question Pool | Topic: T5A
T5A02T5A

Electrical power is measured in which of the following units?

Deep Dive: T5A02

The correct answer is B: Watts. Electrical power is measured in watts (abbreviated as 'W'). Power represents the rate at which electrical energy is used or converted - how much energy per unit time. Power is calculated as Voltage × Current (P = E × I). One watt equals one joule per second. When you see specifications like '50 watts output' or '100W transmitter', that's referring to electrical power. Power is important in amateur radio for understanding transmitter output, power supply requirements, and energy consumption. Watt-hours (Wh) measure energy (power × time), not power itself.

Why Other Answers Are Wrong

Option A: Incorrect. Volts measure voltage, not power. Voltage is electrical pressure, while power is the rate of energy use. Option C: Incorrect. Watt-hours measure energy (power × time), not power itself. Power is measured in watts, energy in watt-hours. Option D: Incorrect. Amperes measure current, not power. Power = Voltage × Current, so you need both voltage and current to calculate power.

Exam Tip

Power = Watts. Remember: Electrical power is measured in watts (W). Power is the rate of energy use, while watt-hours measure total energy.

Memory Aid

**P**ower = **W**atts (think 'P = W' = Power = Watts)

Real-World Example

Your transceiver outputs 50 watts of RF power when transmitting. This means it's using electrical energy at a rate of 50 watts. If you transmit for 1 hour, you've used 50 watt-hours of energy. The 'watts' tells you the power (rate), while 'watt-hours' tells you the total energy consumed over time.

Source & Coverage

Question Pool: 2022-2026 Question Pool

Subelement: T5A

Reference: FCC Part 97.313

Key Concepts

Electrical power Watts Power measurement Electrical units

Verified Content

Question from the official FCC Technician Class pool. Explanation reviewed by licensed amateur radio operators and mapped to the T5A topic.