[Physics] Resistors are used to reduce current to prevent light bulbs from “exploding” but it’s also said that “current remains same at all points in a circuit”

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Resistors are used to reduce current in order to prevent light bulbs and other electrical components from “exploding”, but it is also said that “current remains the same at all points in a series circuit”.

Then what's the point of using resistor when the current will remain the same, and as it would remain the same, the light bulb would still receive that high current which could cause it to explode.

So, again, why are we using resistors? If current is still going to be the same, what's the point? The light bulb would still explode if it will not be receiving a lower current. Also, I'm talking about the series circuit, not a parallel one.

Best Answer

You seem to be proposing that all series circuits have the same current. That isn't true.

The equivalent resistance of a set of resistor in series is $$R_{eq}=\sum_iR_i$$ i.e. you just find the sum of all the resistances. If they are all ohmic then the current that flows through the circuit with voltage source $V$ is given by $$I=\frac{V}{R_{eq}}$$ Therefore, the more resistors you add the smaller the current through the circuit will be.

The power dissipated by a lightbulb in this circuit is given by $P=I^2R$, where $R$ is the lightbulb's resistance. Therefore, a lower current means less power dissipation, and less of a chance of exploding.

The current is constant throughout a series circuit (i.e. at all points in the circuit). That doesn't mean all series circuits have the same current no matter what. Certainly adding more resistance changes the current. That is why is is called resistance. It resists the flow of current.