A small resisrtor say a lamp a usually put in parallel to the current carrying coil in an electromagnet. Why?

A small resistor is usually put in a parallel t the current carrying coil of an electromagnet as shown in the figure. What purpose does it serve?

Do all current carrying conductors emit electromagnetic waves? Explain.

Does a current carrying circular coil produce uniform magnetic field?

Derive an expression for the magnetic field.at the centre of a current carrying coil.