The peak current flowing through a \( 25\,\Omega \) resistor connected to an ac source of frequency 60 Hz is 2.5 A. What is the rms voltage across the resistor?
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → 44 V
For a sinusoidal current the rms value is \( I=i_m/\sqrt{2} \), and across a resistor Ohm’s law holds for rms values, \( V=IR \). The frequency does not enter, since the resistance of a resistor is the same at every frequency.
\( \begin{aligned} I &= \frac{i_m}{\sqrt{2}} \\ &= \frac{2.5\,\mathrm{A}}{\sqrt{2}} \\ &\approx 1.77\,\mathrm{A} \end{aligned} \)
\( \begin{aligned} V &= IR \\ &= 1.77\,\mathrm{A}\times25\,\Omega \\ &\approx 44\,\mathrm{V} \end{aligned} \)