Circuit Analysis: Voltage Direction & Power Questions

[Air]

I have the following circuit:

My question is, what do I take the voltage direction to be? For the center component, it is 200V in a positive direction being upwards so does that mean that for the other components (20A and 10A), it is also in that direction?

Thanks in advance.


EDIT: I have one more question - When voltage is in the direction of current, is the power equal to +Vi or -Vi?

 

[Delphi51]

I don't understand the components - are they batteries, meters or what? Hmm, can't be meters because you can't run 80 A through a Voltmeter or put 200 Volts across an Ammeter!

It appears that the + and - markings indicate the voltage polarity and the arrows indicate the direction of standard (positive) current.

 

[nlightner]

I would like to clarify that the direction of voltage and current are not always the same. Voltage is a measure of potential difference between two points in a circuit, while current is the flow of electric charge. In your circuit, the voltage direction for the center component may be upwards, but it could be different for the other components depending on how they are connected. It is important to consider the direction of current flow when analyzing a circuit.

Regarding your second question, the power in a circuit is determined by both the voltage and current. The formula for power is P = VI, where V is the voltage and I is the current. The power will be positive if both the voltage and current have the same direction, and negative if they have opposite directions. Therefore, the power can be either +Vi or -Vi depending on the direction of voltage and current in the circuit.

I hope this helps clarify your questions. Remember to always consider the direction of current flow when analyzing a circuit and use the power formula to determine its value.