Question

The armature of dc motor has 20Ω 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. 190 V
• B. 150 V
• C. 170 V
• D. 120 V

Answer 1

The correct option is A 190 V

We know that,

$i=\frac{E-e}{R}$

where $E=emf$ and $R=$ Resistance

$1.5=\frac{220-e}{20}e=190V$