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From what I've readed, a resistor is a component which limit the current in a circuit. Supposing that I've a load that is rated for 12v 500mA, if I put a resistor to limit the current to, for example, 100mA what will happen to the load that expect to draw more current? Will it drop more voltage?

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  • \$\begingroup\$ The 12 V will be divided between the two loads. The voltage dropped across each will be proportional to the resistance. See Ohm's Law and potential divider. \$\endgroup\$ – Transistor Jun 29 '16 at 15:23
  • \$\begingroup\$ "a resistor is a component which limit the current in a circuit" That is true only under a very loose interpretation of "limit", and in some develishs circuits the relation might even be reversed. \$\endgroup\$ – Wouter van Ooijen Jun 29 '16 at 17:47
  • \$\begingroup\$ "to limit the current to, for example, 100mA" now you are overinterpreting the term "reduce". A resistor does not reduce the current to a specific value. Cmpare to: I put a brake on the cyclists wheel to reduce its speed to 3 km/h (note that a simple brake will not do that). Now what happens when he hits a wall? Of course his speed will no longer be 3 km/h. \$\endgroup\$ – Wouter van Ooijen Jun 29 '16 at 17:49
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Simple ohms law. V = I * R. If you reduce the current I through the load, you will have a proportional drop in voltage V. For simple resistive loads, inductive loads like motors are a bit more complex, but still a general rule of thumb.

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