力率とは？|交流電力はなぜ力率cosθをかけなくてはいけないのか？

The formula for AC power is P = VIcosθ. Do you vaguely remember this cosθ as the "power factor"? But why isn't simply multiplying voltage and current sufficient? Why does the angle θ appear? — We'll unravel the "why" step by step, starting with the wave shift. While DC power can be calculated as P = VI, AC power requires cosθ. Understanding this reason will transform the power factor from a formula to be memorized into a concept that makes perfect sense. ▼What you'll learn in this video Why the method of calculating power differs between DC and AC How the voltage and current waves shift when coils and capacitors are present Why energy returns to the power source when the waves are shifted What does it mean for active power to decrease? Why is θ in cosθ an "angle" (relationship with a rotating arrow)? Understanding from the waveform why power becomes zero when θ = 90° ▼Recommended for: Those studying for the Class 3 Electrical Engineer Examination independently Those who know the power factor formula but don't understand its meaning Those who are confused about "why we multiply by cosθ" Those struggling with AC circuit calculations Power factor is a crucial topic related to all three subjects of the Class 3 Electrical Engineer Examination: Theory, Power, and Machinery. If you grasp this by "understanding its meaning" rather than "memorizing the formula," related topics such as reactive power, apparent power, and power factor correction capacitors will all become clearer. #ElectricalEngineerLevel3 #ChiefElectricalEngineer #PowerFactor #ACPower #Theory