Question

The rms value of the current in a wire which carries a d.c current of 10A and a sinusoidal alternating current of peak value 20 A is

• A. 10 A
• B. 14.14 A
• C. 15 A
• D. 17.32 A

Answer 1

The correct option is D 17.32 A

RMS value of dc current
$=10A=I_{dc}$

RMS value of sinusoidal current
$=\left(\frac{20}{\sqrt{2}}\right)A=I_{ac}$

RMS value of resultant,

$I_R=\sqrt{I_{dc}^2+I_{ac}^2}$

$=\sqrt{{10}^2+(\frac{20}{\sqrt{2}}{)}^2}=17.32A$