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QUESTION: -Explain how Lenz's Law inhibits the operation of an
electric motor
Answer.
Each loop in the winding of an electric motor changes its orientation
in the magnetic field as it rotates under the influence of the torque
caused by the interaction of the current carrying loop with the
magnetic field. The changing orientation causes an induced EMF to be
in the loop by Faradays Law. The direction of the EMF acording to
Lenz's law will be to be against the direction of the current so
that the torque is be reduced because the magnetic force in the
current carrying loop which depends on the current is reduced.
-Explain why AC current must be used in a transformer
Answer.
AC must be used because it creates an alternating (changing) magnetic
flux in one wire which by Faradays Law produces a EMF in the second
wire. In this way energy is transfered from one loop to another via
the magnetic field.
-Compare FM and AM radio waves (how the radio waves travel from the
transmission tower to your radio)
Answer.
FM (frequency modulated) waves travel within a certain band width of
frequency. Each station is alloted a bandwidth with some mean
frequency. By letting the signal vary within the band information is
propagated to a radio which is tuned to this frequency band.
AM (amplitude modulated) waves are sent at a fixed frequency and the
information is propagated by varying the amplitude at this fixed
frequency.
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