The science kit by John Adams also won the Smart Explore category.
Electro Mag uses magnets to create more than 40 experiments, teaching children as young as eight about electronics, magnetics and circuits.
Smartlab Motor Mania won the Smart Build category; the Smart Play category went to X-zylo Launcher; and Winomino, a racing jigsaw game received the Smart Play Highly Commended award together with Traffic Control Airport.
35 children tested the toys before presenting their findings to a panel of five judges. Each entry had to suit children between the ages of six and 14 and assist children in learning about science in some way.
Jean Franczyk, head of learning for the Science Museum said: “There was great overall quality among the entries but in the end there was a clear winner. Electro Mag really captured the ‘serious fun’ approach of the Science Museum that emphasises learning by doing”.