Strong Electromagnet

An electromagnet powered by normal batteries is so strong that two people cannot pull it apart.

How does it work?
The battery is almost short-circuited, and a current of around 1-2 Amperes flows. This generates an extremely high magnetic field in the coil. Electromagnets very efficiently convert the stored energy in the battery into power. There, electric motors can be operated with an efficiency of 95%, whereas combustion engines only reach around 25%.