Loads on a Power Source

Can anyone explain why turning on another load in an electrical system causes the others to diminish in intensity? I notice in my car when it's running that the transmission indicator display dims and brightens with the on/off pattern of the turn signals. Is this because the extra amps result in an inability of the system to maintain voltage? How could this be if the car has so many other loads to carry on the system and the alternator compensating? I also have seen the same thing at home. My microwave light and timer display dim and brighten with the on/off of the microwave power during reduced power cooking. This too seems odd even though its so many watts because I am not using the maximum amps for the breaker. Additionally, the whole house could surely be demanding more amps on the utilty company's power supply, as could the community. Is this for some reason a strain on 120V?

Reply to
inboxjm
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Using the car as an example:

A +12 ---[R]---+---> to turn signal | +---> to transmission indicator

[R] in the above diagram will lower the voltage at the point labeled A by an amount equal to the current drawn by the turn signal times the value of R. R is the resistance in the wiring, fuse block and connectors between point A and the battery. When the turn signal is off it draws no current and the voltage at point A is higher because no voltage is dropped in the resistance. When the signal turns on, it draws current through the resistance and the voltage at point A lowers.

Ed

Reply to
ehsjr

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