Q. What is the $r.m.s.$ value of an alternating current which when passed through a resistor produces heat which is thrice of that produced by a direct current of 2 amperes in the same resistor
A) $6\ amp$
B) $2\ amp$
C) $3.46\ amp$
D) $0.66\ amp$
Explanation
(c) Heat produced by ac $= 3 \times$ Heat produced by dc
$\therefore i_{rms}^{2}Rt = 3 \times i^{2}\ Rt \Rightarrow i_{rms}^{2} = 3 \times 2^{2}$
$\Rightarrow i_{rms} = 2\sqrt{3} = 3.46\ A$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.