Parallel and Series circuits and current

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Homework Help Overview

The discussion revolves around understanding the behavior of bulbs in parallel and series circuits, specifically focusing on how the addition of components affects brightness and current. The original poster presents two questions aimed at exploring these concepts without delving into mathematical equations.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • The original poster attempts to reason through the effects of adding a bulb in parallel on the brightness of existing bulbs and the current in the circuit. Some participants question the impact of voltage drop across components and whether the brightness of parallel bulbs is affected by the addition of another parallel component.

Discussion Status

Participants are actively engaging with the original poster's reasoning, providing feedback and prompting further consideration of the assumptions made regarding voltage and current in the circuit. There is a focus on clarifying how changes in the circuit configuration influence the overall behavior.

Contextual Notes

The original poster emphasizes a conceptual understanding over mathematical calculations, which may limit the depth of analysis regarding current values and voltage drops in the circuit.

motyapa
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Homework Statement



2 different questions that I'm using to test my understanding of the physics concepts rather than the math:

1)
How does the brightness of bulb A compare to that of bulb C?
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After D is added how does the brightness of bulb A change?
Does the brightness of B change?
Does the current through the battery change?
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2)
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What is the current through 1, 2, 3?
What is the current through C, D, E?

Homework Equations



Less math more conceptual, so no equations to use (plus we haven't learned any equations for circuits yet)

The Attempt at a Solution


[/B]
so for 1a I said that bulb A is brighter than bulb B/C because B & C are in parallel with each other, it increases the current through bulb A.

1b I said bulb A becomes brighter, because the addition of bulb D increases the current throughout the whole circuit. Bulb B does not change brightness because the current through its portion does not change, and the current through the battery increases since the overall current through the whole circuit increased.

For 2 I said the current through 1 is 60, equal to the bulb. For 2 I said it's 30, since 30 goes through B, which means 30 will go through C, so 30 reaches the battery equal to the bulb. For 3 I said it's 120, because D and E both have 60 mA since they're in parallel, so the total is 120.

Does my reasoning of these concepts seem good or am I off on something?
 
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All good, except how the addition of D affects B in 1. Think about the voltage drop across A.
 
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I used this website to try and help me to reach my answer: http://epb.apogee.net/foe/fcspp.asp

it seems like adding more in parallel shouldn't change how bright the other parallel ones are? I'm confused why B should change.
 
Last edited by a moderator:
motyapa said:
I used this website to try and help me to reach my answer: http://epb.apogee.net/foe/fcspp.asp

it seems like adding more in parallel shouldn't change how bright the other parallel ones are? I'm confused why B should change.
You are assuming the voltage across B does not change.
 
Last edited by a moderator:

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