power drain?

[pepocho]

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[sillyjoe]

I just found it easier to note that P = IV, so power drain is given by this function. You can then substitute V = IR to get a few working definitions:

P = I^2*R
P = V^2 / R

Power will drain more when P increases. Power is just the (change in work / time) or the (change in energy / time). All you are saying is that the rate at which the energy is dissipating for a said resistor will increase or decrease based on the aforementioned functions.

 

[DrknoSDN]

I understand that increasing current will lead to more power being dissipated or "lost" but I don't understand how decreasing resistance would not lead to LESS power being dissipated.

I think I know what your asking because I almost answered that lowering resistance would reduce power... The problem is that most all circuits are using a standard constant voltage battery. That is very important because if you increase current you would increase power, but if you decrease a resistor the current will just increase to counter the drop in resistance. See the equation below.

Also: http://hyperphysics.phy-astr.gsu.edu/hbase/electric/elepow.html#c1

Numbers:
12 volt = 1 amp * 12 ohm
Power = 12 volt * 1 amp = 12 watt
Power = 1 amp * 1 amp * 12 ohm = 12 watt

12 volt = 2 amp * 6 ohm
Power = 12 volt * 2 amp = 24 watt
Power = 2 amp * 2 amp * 6 ohm = 24 watt

V=IR must hold true so if voltage is constant and you drop the resistance then current should increase to compensate. If it didn't you would be breaking ohms law, or you would need to have an variable voltage battery but that is not usually what is presented in circuits.

Constant-current variable-voltage batteries exist but thay are far less common and less safe than constant voltage batteries.
(Not electrician, so don't hate if that's not accurate, just remember watching something on youtube about constant current batts being deadly)

 

[pepocho]

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[sillyjoe]

thanks guys. along with this and TBR explaining it more thoroughly later made it more simple to understand. I think one of TBR's worst faults is that it tends to bring up complicated topics with little explanation and doesn't have the courtesy to say , "hey we will go in more depth later!"

Everything they do is more in depth. Usually a lot more in depth than what you would need for the MCAT. Just subtract the pages of EK from BR and that is all of the "extra/more in depth" material. EK expects you to be able to apply everything you learnt to more complex cases by distilling it. TBR gives you MORE detail so there is at least some level of an understanding when you get to a complicated passage.

I happen to like TBR because it allows you to master a topic more in depth so when you get to a complicated passage it seems rather easy relatively.

edit: Sorry for the run-on sentences. I'm mobile.

 

[pepocho]

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[sillyjoe]

Nah, its cool. I love TBR. but sometimes I find myself confused about a certain concept, and I spend 15-30 minutes looking for clarification on the internet, only to find an explanation five pages later haha Either way, I am in too deep! I am already nearly 2/3 through sn2ed's study plan!