An electric motor operating on a `60 V` dc supply draws a currrent of `10A`. If the effeciency of the motor is `50%`, the resistance of its winding is

Options

A. `3Omega`
B. `6Omega`
C. `15Omega`
D. `30Omega`

Answer

A

Explanation

Efficiency `eta=50%` so `e=E//2`
and `i=(E-e)/(R ) impliesi=(E-E//2)/(R )=(E)/(2R)`
`impliesR=(E)/2i)=(60)/(2xx10)=3Omega`