Sinusoidal waveform conversion: A sinusoidal voltage has a peak-to-peak value of 100 V. Determine its root-mean-square (RMS) value, keeping the basic AC relationships explicit.
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A50 V
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B70.7 V
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C35.35 V
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D141.41 V
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E25 V
Answer
Correct Answer: 35.35 V
Explanation
Introduction / Context:RMS values are essential in AC circuit analysis because they relate sinusoidal voltages and currents to equivalent DC heating effects. Given a peak-to-peak voltage, we often need to compute RMS to size components and evaluate power accurately.
Given Data / Assumptions:
- Peak-to-peak voltage V_pp = 100 V.
- Pure sinusoidal waveform.
- Standard RMS relation for sinusoids applies.
Concept / Approach:
For a sinusoid, V_pp = 2 * V_m, where V_m is the positive peak (amplitude). The RMS value is V_rms = V_m / √2. Therefore, convert V_pp to V_m, then divide by √2 to obtain the RMS value.
Step-by-Step Solution:
Find amplitude: V_m = V_pp / 2 = 100 / 2 = 50 V.Use RMS relation: V_rms = V_m / √2.Compute: V_rms = 50 / √2 ≈ 50 / 1.4142 ≈ 35.35 V.Thus the RMS value is approximately 35.35 V.Verification / Alternative check:
Cross-check: If V_rms = 35.35 V, then V_m = V_rms * √2 ≈ 50 V and V_pp = 2 * V_m = 100 V, matching the given peak-to-peak value.
Why Other Options Are Wrong:
- 50 V: That is the peak, not the RMS.
- 70.7 V: That would be RMS if the peak were 100 V, but here 100 V is peak-to-peak.
- 141.41 V: That is 2 * 100/√2, not applicable here.
- 25 V: No standard relation yields this value from 100 V peak-to-peak.
Common Pitfalls:
- Confusing V_pp with V_m; always halve V_pp to get the amplitude before converting to RMS.
Final Answer:
35.35 V