Q. The internal resistance of a primary cell is 4$\ \Omega$ . It generates a current of 0.2 A in an external resistance of 21 $\Omega$. The rate at which chemical energy is consumed in providing the current is
A) 0.42 J $s^{- 1}$
B) 0.84 J $s^{- 1}$
C) 1 J $s^{- 1}$
D) 5 J $s^{- 1}$
Explanation
(c) Chemical energy consumed per sec = heat energy produced per sec.
$I^{2}(R + r) = (0.2)^{2}(21 + 4) = 1\ J\ s^{- 1}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.