# Resistor waste energy

1. ## Resistor waste energy

Resistor is found in a lot of circuits, however, are they actually making waste of energy? since they are just heating up itself!!

Let say a resistor in a voltage divider and a resistor in series with a LED just for dropping the supply voltage

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2. ## Re: Resistor waste energy

This is correct. However, in many cases the cost of the wasted energy is less than the cost of the components that would replace it.

3. ## Re: Resistor waste energy

Agree...
Resistor component is for regulating/control purpose.
Energy is consumed for the purpose.

I guess we cannot run away from it.
Everything have resistance.

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4. ## Resistor waste energy

resistors have other functions like RC couples and filters....

they dont just waste energy

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5. ## Resistor waste energy

They also play an important role in producing a voltage across it... when the o/p in current..

Eg: In an current gain (amplifier) ckt, when you need o/p as a voltage, then you need to collect it with a load resistance... here resistance plays an imp role...

Agree @siongboon:
They also act as regulating devices...
Say you dont want current to flow through a particular branch, you fill it up with a resistance so that current does not enter it.....

6. ## Re: Resistor waste energy

many times we have to connect a resistor in circuits just because to low down the voltage. it is the requirement to drive components that have small voltage ratings.

7. ## Re: Resistor waste energy

Yes.
And that is bcoz some components cant handle tat much of voltage, in terms that, it cant handle this much of power..... and thus heat..produced by it (power dissipation) So we do that before It enters the components...

We also add resistances (add or subtract>>Series r parallel) so as to match the i/p--o/p impedance... That is called as impedance matching and is done so that maximum power can bee transferred from source to the load

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8. ## Resistor waste energy

also they are needed for the production of voltage in accordance with the ohms law

9. ## Re: Resistor waste energy

Originally Posted by luckyvictor
Resistor is found in a lot of circuits, however, are they actually making waste of energy? since they are just heating up itself!!
Let say a resistor in a voltage divider and a resistor in series with a LED just for dropping the supply voltage
Did you hear about the sentence "conservation of energy"?
With other words: This "waste" of energy by heating up a resistor is exactly what we want (because it cannot be avoided). We cannot take out energy from the voltage source and deliver it to a (for the sake of simplicity) resistive circuit without consuming this energy in form of heating up.

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