What Will Happen to a Lamp Connected to AC & DC?

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Discussion Overview

The discussion revolves around the effects of connecting alternating current (AC) and direct current (DC) sources to a lamp, exploring various scenarios and configurations. Participants express uncertainties and pose questions regarding the behavior of the lamp under different electrical conditions, including the mixing of AC and DC, and the implications of each type of current on the lamp's operation.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation
  • Homework-related

Main Points Raised

  • Some participants question what happens when a 3V AC source and a 3V DC source are connected together with a diode and a lamp.
  • Others emphasize the need for a complete circuit to allow current flow, suggesting that the configuration described lacks clarity.
  • One participant expresses doubts about the consequences of mixing AC and DC, asking for clarification on multiple scenarios involving different current types applied to a bulb.
  • Some participants assert that a bulb will light up with direct DC and AC, but the behavior differs, with AC causing the bulb to flash at the frequency of the AC signal.
  • There are claims that mixing AC and DC sources in series or parallel is not advisable, with some participants suggesting that they can theoretically be combined under certain conditions.
  • One participant mentions that the bulb would not break under direct DC, countering another's assumption that it would.
  • Participants discuss the importance of visual aids, such as diagrams, to better understand the concepts being debated.
  • There are suggestions to draw graphs to illustrate the voltage and current behavior across the bulb when AC and DC are mixed.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the effects of connecting AC and DC to a lamp, with multiple competing views and uncertainties remaining regarding the outcomes of various configurations.

Contextual Notes

Some participants express confusion over the lack of diagrams or clear descriptions of the electrical configurations being discussed, which may hinder understanding. There are also references to the need for specific circuit setups to evaluate the scenarios properly.

Who May Find This Useful

This discussion may be of interest to individuals studying electrical engineering, physics, or anyone curious about the behavior of electrical components when subjected to different types of current.

rama1001
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Hi,
I am just thinking and i got doubt that if one wire carries AC(3V) and other wire carries DC(3V) and on the other side if you conntect together followed by a diode and last with one lamp.

What will happen in that situation to lamp.
 
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rama1001 said:
Hi,
I am just thinking and i got doubt that if one wire carries AC(3V) and other wire carries DC(3V) and on the other side if you conntect together followed by a diode and last with one lamp.

What will happen in that situation to lamp.

Could you post a sketch? And remember, to have a current you need a loop. So you won't have just one "DC wire" or "AC wire". You would need two wires to make a DC current flow around that loop.
 
There is no real schematic, just i am thinking like if u have 3V DC source and 3V AC source connected to gether and other ends are connected to a bulb through a diode.

Just i want to know what will happen on that ocation.
 
rama1001 said:
There is no real schematic, just i am thinking like if u have 3V DC source and 3V AC source connected to gether and other ends are connected to a bulb through a diode.

Just i want to know what will happen on that ocation.

I'm sorry, but your description does not make sense to me.

Connected together how? Directly connected (bad)? Connected with a diode between them (still bad)? Connected together with a diode and incandescent bulb between them?
 
regardless to this topic, i have doubt in my mind that what happens if in the form of following scenarios...
1) what happens if AC and DC mixed and given to bulb..
2) what happens if AC and DC(alternating) mixed and given to the bulb
3) what happens if direct DC given to bulb
4) what happens if AC given to the bulb.

these just my mad doubts, there is no background materials or circuits for these reasons. I just wany clarify my mad doubts.
Can anyone help me?
 
rama1001 said:
1) what happens if AC and DC mixed and given to bulb..
2) what happens if AC and DC(alternating) mixed and given to the bulb

As per berkeman, I think you need to give a diagram or something because this just doesn't make much sense.
3) what happens if direct DC given to bulb

The bulb lights up.
4) what happens if AC given to the bulb.

The bulb lights up - but this time it flashes on and off at the frequency of the AC.
 
jarednjames said:
As per berkeman, I think you need to give a diagram or something because this just doesn't make much sense.


The bulb lights up.

The bulb lights up - but this time it flashes on and off at the frequency of the AC.

in the case direct DC, i guessed that bulb will break because usually household things are run by AC.. is this wrong.

Why you need circuit for first two questions ... Its just your opinion and you know our mad instructor asking these questions after lab and if you did not answer these you fail in the subject. I already failed because i did not answer these questions, so it was happened.
Please make it clear for me with your opinion...Thank you so muck for your quick reply:))
 
rama1001 said:
in the case direct DC, i guessed that bulb will break because usually household things are run by AC.. is this wrong.

No, the bulb wouldn't break.
Why you need circuit for first two questions ... Its just your opinion.
Please make it clear for me with your opinion

There's nothing here to give an opinion on. We can only give you the facts if we understand what you are asking.
 
jarednjames said:
No, the bulb wouldn't break.


There's nothing here to give an opinion on. We can only give you the facts if we understand what you are asking.

ok just look at the example and may be it make some sense to you. Could you propose any conclusions for that.in that one is DC and another one as AC source.
 

Attachments

  • #10
well you can't mix a DC and an AC source in series (nor in parallel for that matter)
you would use one or the other

Dave
 
  • #11
davenn said:
well you can't mix a DC and an AC source in series (nor in parallel for that matter)
you would use one or the other

Dave

You couldn't put them in parallel because they would fight. But they can be put in series. That's how you would model a sine wave with a DC offset, for example.
 
  • #12
jarednjames said:
As per berkeman, I think you need to give a diagram or something because this just doesn't make much sense.


The bulb lights up.


The bulb lights up - but this time it flashes on and off at the frequency of the AC.
Correction: Twice the frequency. There are 2 zero crossings per cycle.
davenn said:
well you can't mix a DC and an AC source in series (nor in parallel for that matter)
you would use one or the other

Dave
Practically, you might not be able to put a DC power supply and function generator in series, but you can do it with theoretical, ideal supplies. You end up with the AC signal "riding" on top of the DC voltage.

Example, if your AC goes from -5V to 5V and is applied in series with 10V DC, you end up with the voltage oscillating 5V and 15V.
 
  • #13
i am not at all satisfied with show up. can tell me exactly how the behaviour in all scenarios?
 
  • #14
rama1001 said:
i am not at all satisfied with show up. can tell me exactly how the behaviour in all scenarios?

Well people have tried to help but you haven't listened and provided what they requested.

I'm afraid I can't open .doc files so I can't see what you've done above so I'd recommend PDF if possible.
 
  • #15
Why is it so freakin' hard to find a picture to show him? >.< All I can find on google is AC/DC pictures.
 
  • #18
what you have been taking is really irrelavant to the topic. Just want to know how it behaves in all scenarios. You all are talking about some audio amplifications and DC offset.
 
  • #19
rama1001 said:
what you have been taking is really irrelavant to the topic. Just want to know how it behaves in all scenarios. You all are talking about some audio amplifications and DC offset.

rama, V=IR. When there is current flowing through the incandescent bulb in either direction, it will start to light, right? And the more current, the more light, right? What is the problem in that understanding?

Draw yourself a graph of the voltage sum across the bulb as a function of time (or simulate it). The bulb has some resistance, so the voltage V(t) will generate an I(t), which contributes to lighting the bulb.
 
  • #20
berkeman said:
rama, V=IR. When there is current flowing through the incandescent bulb in either direction, it will start to light, right? And the more current, the more light, right? What is the problem in that understanding?

Draw yourself a graph of the voltage sum across the bulb as a function of time (or simulate it). The bulb has some resistance, so the voltage V(t) will generate an I(t), which contributes to lighting the bulb.

Its ok with that conclusion but what happens if AC and DC are given to bulb. Just i want to general idea whta happens id they bothe are mixed?
 
  • #21
rama1001 said:
Its ok with that conclusion but what happens if AC and DC are given to bulb. Just i want to general idea whta happens id they bothe are mixed?

You've already been told.

Posts 12, 16 and 17.

If you draw the graph as per 19 you'll see what happens.
 

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