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Ch 31: Alternating Current
Young & Freedman Calc - University Physics 15th Edition
Young & Freedman Calc15th EditionUniversity PhysicsISBN: 9780135159552당신이 사용하는 게 아니라요?교과서 변경
모든 교과서Young & Freedman Calc 15th EditionCh 31: Alternating Current문제 19a
31장, 문제 19a

The power of a certain CD player operating at 120 V rms is 20.0 W. Assuming that the CD player behaves like a pure resistor, find the maximum instantaneous power.

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Understand that the CD player is modeled as a pure resistor, which means it follows Ohm's Law. The power formula for a resistor is P = V^2 / R, where P is the power, V is the voltage, and R is the resistance.
Given that the CD player operates at 120 V rms and has a power of 20.0 W, use the formula P = V_rms^2 / R to find the resistance R. Rearrange the formula to R = V_rms^2 / P.
Calculate the resistance using the given values: R = (120 V)^2 / 20.0 W.
To find the maximum instantaneous power, recall that the maximum power in an AC circuit occurs at the peak voltage, which is V_peak = V_rms * sqrt(2).
Use the formula for instantaneous power P_max = V_peak^2 / R to find the maximum power. Substitute V_peak and the resistance R calculated earlier into this formula.

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주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

RMS Voltage

RMS (Root Mean Square) voltage is a measure of the effective value of an alternating current (AC) voltage, equivalent to a DC voltage that delivers the same power. It is calculated as the square root of the average of the squares of the instantaneous values over one cycle. For a sinusoidal waveform, RMS voltage is 0.707 times the peak voltage.
추천 영상:
07:14
RMS Current and Voltage

Power in Resistors

Power in resistors is calculated using the formula P = V^2/R, where P is the power, V is the voltage across the resistor, and R is the resistance. In AC circuits, the power can also be expressed using RMS values, as P = Vrms^2/R, which gives the average power consumed by the resistor over time.
추천 영상:
06:00
Power

Instantaneous Power

Instantaneous power in an AC circuit is the power at any given moment, calculated as p(t) = v(t) * i(t), where v(t) is the instantaneous voltage and i(t) is the instantaneous current. For a pure resistor, the maximum instantaneous power occurs at the peak voltage and current, which is twice the average power calculated using RMS values.
추천 영상:
06:00
Power
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