Q. The armature of dc motor has $20\Omega$ resistance. It draws current of 1.5 ampere when run by $220\ volts$ dc supply. The value of back e.m.f. induced in it will be
A) $150\ V$
B) $170\ V$
C) $180\ V$
D) $190\ V$
Explanation
(d) $i = \frac{E - e}{R} \Rightarrow 1.5 = \frac{220 - e}{20} \Rightarrow e = 190\ V$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.