What are four things Nikola Tesla Invented?

Here is one:

In 1882, Serbian inventor Nikola Tesla identified the rotating magnetic induction field principle used in alternators and pioneered the use of this rotating and inducting electromagnetic field force to generate torque in rotating machines. An AC motor is an electric motor that is driven by an alternating current. It consists of two basic parts, an outside stationary stator having coils supplied with alternating current to produce a rotating magnetic field, and an inside rotor attached to the output shaft that is given a torque by the rotating field.