Math Problem Statement

B) Engineers do not use the average voltage. They use the root mean square voltage defined by V = paverage of (V 2). Find V in terms of V0. (Take the average over 1 second.)

(c) The standard voltage in an American house is 110 volts, meaning that V = 110. What is V0?

Solution

To find the root mean square (RMS) voltage VV in terms of the peak voltage V0V_0, we follow these steps:

Part (B)

  1. Definition of RMS Voltage: The RMS voltage is given by: Vrms=1T0TV(t)2dtV_{\text{rms}} = \sqrt{\frac{1}{T} \int_0^T V(t)^2 \, dt} where TT is the period of the signal, and V(t)V(t) is the instantaneous voltage. In this case, we take the average over 1 second.

  2. Instantaneous Voltage: If we assume the voltage V(t)V(t) is sinusoidal (which is common in AC circuits): V(t)=V0sin(2πft)V(t) = V_0 \sin(2 \pi f t) where V0V_0 is the peak voltage and ff is the frequency of the AC signal.

  3. RMS Voltage Formula: The formula for the RMS value of a sinusoidal waveform is: Vrms=V02V_{\text{rms}} = \frac{V_0}{\sqrt{2}}

Part (C)

Given:

  • The RMS voltage in an American house is Vrms=110V_{\text{rms}} = 110 volts.

Using the formula: V0=Vrms×2V_0 = V_{\text{rms}} \times \sqrt{2}

Substituting Vrms=110V_{\text{rms}} = 110: V0=110×2110×1.414155.4 voltsV_0 = 110 \times \sqrt{2} \approx 110 \times 1.414 \approx 155.4 \text{ volts}

Summary

  • (B) The RMS voltage VV in terms of the peak voltage V0V_0 is V=V02V = \frac{V_0}{\sqrt{2}}.
  • (C) If the RMS voltage is 110 volts, then the peak voltage V0V_0 is approximately 155.4 volts.

Would you like more details or have any questions?

Here are 5 related questions to expand on this topic:

  1. What is the physical significance of the RMS voltage in AC circuits?
  2. How does the RMS value differ for different waveforms (e.g., square, triangular)?
  3. What is the peak-to-peak voltage for the given RMS voltage?
  4. How would the RMS voltage formula change if the waveform were not sinusoidal?
  5. Why is RMS voltage used instead of average voltage in AC power calculations?

Tip: RMS values are crucial in AC circuits because they allow direct comparison with DC circuits in terms of power delivery.

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Math Problem Analysis

Mathematical Concepts

Root Mean Square (RMS) Voltage
Sinusoidal Waveforms
AC Circuit Analysis

Formulas

RMS Voltage Formula: V_rms = sqrt(1/T ∫_0^T V(t)^2 dt)
Instantaneous Voltage: V(t) = V0 sin(2πft)
RMS for Sinusoidal Wave: V_rms = V0 / sqrt(2)
Peak Voltage Formula: V0 = V_rms * sqrt(2)

Theorems

Root Mean Square (RMS) Theorem

Suitable Grade Level

Grades 11-12 (Advanced High School) / Early College