Brilliant Crazy DC motor life hacks

Brilliant plumage in peacock is a

Describe the principle, construction and working of a DC motor with the help of a diagram.

What causes the rectangular coil in a D.C. motor to rotate? Explain.

Why are magnets with concave shaped poles used in a D.C. motor? What happens if magnets with flat poles are used in it ?

The armature of a DC motor has 20Omega resistance. It draws a current of 1.5 A when run by 200 V DC supply The value of back emf induced in it will be