Does low current make a light dimmer

Main Question or Discussion Point

If two light bulbs have the same voltage but one with a lower current does it make one dimmer than the other? I’m confused why lights in parallel circuits don’t get dimmer even tho there is less current. Thx for replying

Related Classical Physics News on Phys.org
berkeman
Mentor
There are multiple interpretations of your question, so it would help if you could clarify so we can give you the best answer. Some starting points:
• The light output of a bulb is pretty closely tied to the power it dissipates
• Higher voltage light bulbs (like 220V bulbs versus 110V bulbs) will have a higher resistance for the same output brightness and power consumed
• Light bulbs placed in parallel on an AC Mains circuit do not generally dim as more bulbs are installed on that circuit, because the wiring has been sized (by building code regulations) to be large enough (in conductor diameter) that the voltage drop across the wires from the extra power loading does not change the delivered AC Mains voltage very much
Hope that helps you to respond to clarify your question.

So maybe I should rephrase to: does the amount of current passing through the light bulb (I) affect its brightness? Sorry if I am still being unclear:(

berkeman
Mentor
So maybe I should rephrase to: does the amount of current passing through the light bulb (I) affect its brightness? :(
Yes, the amount of current through an incandescent light bulb is the primary indicator of the brightness of the light emitted.

Do you have a particular situation in mind? Would you like to see more equations showing the electrical and light output behaviors? We're happy to help you start to understand this.

Dale
Mentor
I’m confused why lights in parallel circuits don’t get dimmer even tho there is less current.
As @berkeman said, the brightness is indeed determined primarily by the current. The fact that the lights do not get dimmer in a parallel circuit indicates that there is not less current.

I am confused since my textbook says current in parallel circuits are shared between junctions. XD . Am I missing something or should I lodge a complaint with my teacher? And yes i really would like to start getting familiar with circuits so please recommend some materials to me. Much thx

Attachments

• 39.7 KB Views: 197
Dale
Mentor
The total current is indeed split between the various branches of a parallel circuit, but that does not necessarily imply that the current is less in each branch. It could just as easily mean that the total current is greater instead. In fact, your observation that it does not get dimmer clearly indicates which of those two possibilities occurs.

Ahhh thank you I get it now

So can I say the overall current in a parallel circuit is greater than in a series circuit?

Dale
Mentor
So can I say the overall current in a parallel circuit is greater than in a series circuit?
Yes, with the assumption that the circuit power supply provides the same voltage in both cases. Most power supplies are voltage sources, so that is usually a valid assumption.