What is electromagnetism?. Although electricity is all around us, in every object, it does not exist in large enough ______________ for us to use. There is nothing that gives us electricity directly. Electricity has to be made or _______________.
Although electricity is all around us, in every object, it does not exist in large enough ______________ for us to use. There is nothing that gives us electricity directly. Electricity has to be made or _______________.
In 1820, a Danish scientist named Hans Oersted noticed that a wire with an electric _______________ running through it, acted like a magnet because it made a needle on a compass move. Oersted realized that the current flowing ___________ the wire was producing a magnetic effect. This was the discovery of ___________________.
If a coil of __________ is wrapped around a metal object and connected to an
energy source, the metal object will become ___________________, forming an electromagnet. The electromagnet will attract magnetic materials and can be made stronger by ________________ the number of coils of wire. When the flow of electricity is stopped, the electromagnet _________ its power. Electromagnets, therefore, are only _________________ magnets. They only work when electricity is _______________. Electromagnets are used in motors and many other useful devices such as doorbells, speakers, and one very important instrument, the telephone, invented by _____________________________________ in 1876. Today, enormous electromagnets are used in scrap yards. Can you think what they are used for?
Our ability to generate ________________ is due largely to the work of an
English scientist named Michael Faraday. Although Oersted had earlier discovered the relationship between electricity and _______________, it was Faraday who was the first to discover that a magnet could cause an ______________ current to flow through a wire. While he was working with a current of electricity flowing through a wire, he noticed that nails were _______________ to the wires. Faraday thought that if electricity flowing through a wire could produce a _______________ effect, then perhaps the opposite was true. Perhaps a magnetic effect could _____________ an electric current.
By moving a magnet back and forth through a coil of ________, an electric
current flowed through the wire. When Faraday stopped moving the magnet, the electricity ______________ flowing. Faraday had invented the first generator. His generator produced a ________________ when a handle was turned. It consisted of a copper disc which was turned between the __________ of a magnet. Faraday’s work led to the invention of the electric motor and to the development of large power plants to generate _______________________.