# V/I: Power from Potential Difference & Current

• kara123
In summary, the conversation discusses the concept of power and its relationship to voltage, current, and energy. The equation P=(QxV)/(Q/I) is proposed as a way to calculate power, but it is pointed out that the algebra is incorrect. The correct equation for power is P=VI. The importance of checking dimensions and using relevant equations, such as Ohm's law, is emphasized.
kara123
Homework Statement
(a) Derive an expression for power in terms of potential difference and current.
(b) Use the result from part (a) and Ohm’s law to derive an expression for power in terms of current and resistance.
Relevant Equations
p= E/T
V=E/Q
I=Q/T
e=QxV
t=Q/I
p=(QxV)/(Q/I)
=V/I
The expression I came up with for a) is the potential difference divided by current to get power but I have no idea if that is even right if someone could just prompt me in the right direction that would be greatly appreciated

What is "e"? You mean" E"? And the algebra is incorrect in final step. But I like your approach.

yes i ment E

Hi,
Whatever you do, check the dimensions. Do you know how to do that ?
[power] = [energy] per [time]
##\ \ ##[voltage] = [energy] per [charge]
[current] = [charge] per [time]​

For part b) you also need Ohm's law as a relevant equation !

##\ ##

kara123
(QxV)/(Q/I) ≠ V/I

thankyou all for the help figured it out I must have been really tired while doing that algebra because I'm not sure what I was thinking the answer is P=VI

BvU

## What is potential difference?

Potential difference, also known as voltage, is the difference in electric potential energy between two points in an electric circuit. It is measured in volts (V) and is responsible for the flow of electric current.

## What is electric current?

Electric current is the flow of electric charge through a conductive material. It is measured in amperes (A) and is a result of the movement of electrons in an electric circuit.

## What is power?

Power is the rate at which energy is transferred or converted. In the context of V/I, power is the amount of energy per unit time that is delivered to a circuit by the flow of electric current. It is measured in watts (W).

## How are potential difference, current, and power related?

Potential difference and current are directly related to each other through Ohm's law, which states that the current through a conductor is directly proportional to the potential difference across it. Power is then calculated by multiplying the potential difference by the current.

## What factors affect power in a circuit?

The power in a circuit is affected by the potential difference and current, as well as the resistance of the circuit. A higher potential difference or current will result in a higher power output, while a higher resistance will decrease the power output. Additionally, the type and condition of the materials used in the circuit can also impact the power output.

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