the citadel or high fortified area of an ancient Greek city. the Acropolis, the citadel of Athens and the site of the Parthenon.
Electromagnets are used in a number of everyday devices. One useful characteristic of an electromagnet is the fact that you can vary its magnetic force by changing the amount and direction of the current going through the coils or windings around it.ummary. Electromagnets are used in a number of devices, such as loudspeakers and tape recorders. Some electromagnets can be very strong and its power can be readily turned off and on, such as in junk yard electromagnets and electromagnetic locks.
Observe the number of turns in an electromagnet's coil. A simple electromagnet can be made by wrapping a coil of wire around a nail and attaching its ends to a 1.5-volt battery, while commercial electromagnets have sizable cores of one of the magnet materials described above and large coils around them. You can also use the gaussmeter sensor to test the field strength at varying distances from the magnet. 2  Place the sensor at a series of defined distances from the magnet's pole and record the results. 3  This method would be suitable for teaching middle school and high school age students about magnetic fields.