... A dynamo (or electric generator) is a device converting . ... Faraday discovered that by moving a magnet next to a closed electric circuit, or changing the magnetic field passing through it, an electric current could be "induced" to flow in it. ... Faraday's disk dynamo Faraday showed that another way of inducing the current was to move the electric conductor while the magnetic source stood still. ... Faraday's disk dynamo needs a magnetic field in order to produce an electric current. ...