If DC current is quickly stopping and starting/pulsating, will a multimeter give an

J

JB

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average of voltage.? I am testing out the current controlling the speaker on an alarm clock. I know that it beeps. I am guessing that the beeping is caused from current going to the speaker, then stopping, and so on. My multimeter never says the voltage is at 0, it just shows voltage slightly changing ranging from 10-13V. I am confused. Does this slight change cause the beeping sound.
 
The beeping sound is caused by magnetic field variations resulting from the transient current circuit, that propagate to the speaker's buzzer.


The reason that your multimeter is "averaging" the current, is that there is inevitably inductance of the wiring. Inductance acts like an "electrical inertia" that tries to keep currents constant. If currents try to change, they produce back-emf that hinders the change.
 
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