If the RMS current is 20.2 A, what is the peak value?

• A. 14.1 A
• B. 20.2 A
• C. 15.0 A
• D. 28.6 A

Answer: (D)

For a sinusoidal current, the peak value is the RMS value multiplied by the square root of 2. This comes from how RMS measures the effective heating effect of a sine wave, while the peak is the maximum instantaneous current.

So with an RMS of 20.2 A, the peak is 20.2 × √2 ≈ 20.2 × 1.414 ≈ 28.6 A. The peak must be larger than the RMS, which is why 28.6 A is the correct peak value. The other numbers would arise from using the wrong relation (for example, dividing by √2 would give about 14 A, which is not the peak).