How To Produce Electric Current From Magnets (1961)

[Music] this gadget is a balance you can see that it is in Balance now this is a magnet the magnet has no effect on the balance the copper strip around the edge of the balance is connected through these pivot Points to a battery when the switch is closed electric charges will flow through this circuit the flow is shown by this meter the magnet has no effect on the balance until the switch is closed and Electric charges flow through the copper strip at the end of the balance the magnet affects the balance only when there is a current in it it affects the balance with enough Force so that you have to put weight on the other end in this case some sugar to make it balance again here is a magnetic needle removed from a compass it can be affected by another magnet let's see what effect an electric current in a wire will have on the magnetic needle again magnetism and electricity seem to have some connection notice that when the current is turned on the red end of the needle swings toward us with the flow of current reversed the needle swings the other way here's a piece of iron as you can see it's not a magnet but perhaps you know what will happen when we put the iron inside a coil of wire and let Electric charges flow through the coil an electric current can produce a magnetic effect in fact this is called an electromagnet an electromagnet acts as a magnet only as long as electricity is flowing through it here's an electromagnet powerful enough to pick up a load of steel bar s electric currents can produce magnetic effects now let's see if the opposite is true can magnets produce electric currents this coil of wire is not connected to a battery it's connected in circuit with this meter and that's all there is no current in this circuit there are electric charges in the wire and the meter but nothing is making them move and there is electric current only when electric charges are moving watch the meter when this magnet is brought close to the coil there were electric charges flowing through that circuit for a moment there again but in the opposite direction somehow the magnet is making the electric charges in the circuit flow but only when the magnet is moving if we keep the magnet moving we're able to generate a fairly continual current in the [Music] circuit what's making the headlight burn is there a battery no there isn't any battery in this motor [Applause] scooter that's odd the lights don't go out in a car when you turn off the engine what makes the electric current that lights this headlight the answer is magnets the magnets are inside here this is a magnet when the motor is running it makes these magnets move past the coils of wire as they move past the magnets cause the electric charges in the coils to move producing an electric current just as we are doing here here's another device that can be used to produce electric current in this one the magnets don't move instead the coils move in relation to the magnets when the machine is cranked rapidly it produces enough electric current to light a bulb machines that produce or generate electric current are called gener [Applause] Ator you can generate electric current either by moving coils in relation to magnets or by moving magnets in relation to coils we've already seen that a coil or wire with a current running through it can produce magnetic effects could we use this coil instead of a permanent magnet to produce an electric current in the other coil let's see of course we could generate an electric current without moving the coil at all what's generating current now the nails are affected by the electromagnet but the effect is weak if we move the electromagnet closer the effect is stronger when there is a current in the coil the magnetic effect is strong when there is no current the effect is weak in fact there is no magnetic effect At All by opening and closing the switch we are making the magnetic effect weak then strong then weak then strong in other words turning the magnet on and off has the same effect as moving it in and out so we're producing an electric current in this circuit simply by turning the electric current on and off in this circuit water power is used to turn the generators in the PowerHouse of this Dam these huge generators work on the same basic principle as this generator we are producing an electric current here by moving a magnet and basically the same thing is happening here inside these generators magnets are moving past coils producing electric current they are producing a great deal of it enough to light City [Music]