Why Do Homes Have Electrical Outlets with Constant Voltage?

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Discussion Overview

The discussion centers around the question of why homes are equipped with electrical outlets that provide a constant voltage instead of a constant current. Participants explore the implications of this design choice in the context of power distribution, electrical theory, and the operation of various devices.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants note that the current drawn from a voltage source depends on the resistance of the load, referencing Ohm's Law.
  • It is mentioned that while constant current sources have applications in electronics, voltage sources are preferred for power distribution.
  • One participant raises a concern that using a constant current source could lead to varying frequency with load changes, which might affect the operation of devices like synchro motors.
  • Another participant questions how varying frequency in an AC current source would change power output, indicating a lack of understanding of the implications.
  • A participant recalls a physics teacher stating that a constant current AC source would result in non-constant frequency, potentially impacting AC powered motors.
  • There is a correction regarding a typo in the expression of Ohm's Law, with participants engaging in clarifying the correct formulation.

Areas of Agreement / Disagreement

The discussion reflects multiple competing views regarding the implications of constant voltage versus constant current sources, particularly in relation to device operation and power distribution. There is no consensus reached on the best approach or the implications of each method.

Contextual Notes

Participants express uncertainty about the effects of constant current sources on frequency and device performance, indicating a need for further clarification on these technical aspects.

doublemint
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My friend asked me why do houses have electrical sockets that output a constant voltage rather than a constant current.
For the life of me, I couldn't answer it..

Anyone help me out?

Thanks,
DM
 
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doublemint said:
My friend asked me why do houses have electrical sockets that output a constant voltage rather than a constant current.
For the life of me, I couldn't answer it..

Anyone help me out?

Thanks,
DM

The current drawn from the voltage source is dependent on the resistance of the load, according to Ohm's Law:

[STRIKE]V = V x R[/STRIKE] V = I x R

Or

I = V/R

Constant current sources have their applications in electronics, but not in power distribution. You use voltage sources for power distribution.EDIT -- Just to add a bit more... Common power sources like batteries and electric generators are voltage sources, not current sources.
 
Last edited:
doublemint said:
My friend asked me why do houses have electrical sockets that output a constant voltage rather than a constant current.
For the life of me, I couldn't answer it..

Anyone help me out?

Thanks,
DM

I forget now how it works (I'm sure some one can correct me) if you where to use constant current then the frequency would vary with load which would mean certain devices such as synchro motors wouldn't spin at a predictable speed.
 
rollcast said:
I forget now how it works (I'm sure some one can correct me) if you where to use constant current then the frequency would vary with load which would mean certain devices such as synchro motors wouldn't spin at a predictable speed.

If you used an AC current source, why would varying the frequency change the power output (to adjust to the load)? I'm not understanding what you are saying...
 
berkeman said:
If you used an AC current source, why would varying the frequency change the power output (to adjust to the load)? I'm not understanding what you are saying...

I asked my physics teacher this same question one time and he said that if you had a constant current ac source then the frequency wouldn't be constant and that would affect ac powered motors?
 
berkeman said:
The current drawn from the voltage source is dependent on the resistance of the load, according to Ohm's Law:

V = V x R
I'm sure you mean V = I x R.
berkeman said:
Or

I = V/R

Constant current sources have their applications in electronics, but not in power distribution. You use voltage sources for power distribution.


EDIT -- Just to add a bit more... Common power sources like batteries and electric generators are voltage sources, not current sources.
 
Mark44 said:
I'm sure you mean V = I x R.

Oops, thanks for catching my typo, Mark. I'll strikeout and fix my post above. Thanks.
 

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