Brilliant crazy life hacks with Dc motor

Brilliant plumage in peacock is a

On a rainy day a small oil film on water shows brilliant colours. This is due to

An electric motor operating on a 50 V dc supply draws a current of 12 A . If the efficiency of the motor is 30 % ,estimate the resistance of the windings of the motor.

An electric motor operating on 50 volt D.C. supply draws a current of 10 amp. If the efficiency of motor is 40% then the resistance of the winding of the motor is