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Potential Difference

Pawan Asked

“What is meant by potential difference?”

Answer:

“Potential Difference between two points is the difference in Potential between the two points and is equal to the work done per unit charge ion carrying a positive test charge from one point to another against the electric field and without any acceleration”

Differences Between EMF and Potential Difference

What is main relationship between EMF and potiential difference?

Answer: The question is already answered at http://askphysics.com/difference-between-emf-and-pd/

Flow of air?

I’m working on a science project now and I have a doubt,Consider two places(A and B) with a vast temperature difference connected by a insulated pipe,would air flow through the pipe from A to B?lets say A is up in the mountains and B is in the plains,air flows from a cold place to a hot place,doesn’t it?If it does flow, I would like to know how to calculate it’s pressure.If it doesn’t flow,I would like to know the reason for that as well.

Difference between Scalar Product and Vector Product

“What is the difference between dot product and cross product?” [The question was posted by Salman)

Potential Difference – misconception

What actually it means when we say “potential difference across..” ? Does it indicate that the somehow the energy level of electrons across it is less than on the other side or is it just the amount of energy consumption across it. If latter is true then in AC we’ve voltages which dont algebraically add up together to give the applied voltage . reason stated is the phase difference. How can there be phases in something scalar like energy consumption ? (Posted by Thushar)

Answer: As per definition, “Potential difference is defined as the work done per unit charge in carrying a positive test charge between two points against the electric field.”

Just like water flows from a high altitude to low altitude, “current” flows from high positive potential to low positive potential. (And electrons flow in the reverse direction. Though electrons are the actually movable materials contained in a conductor, the direction of current was conventionally defined as the direction of motion of positive charges)

So, when there is a difference in potential the electrons will flow from lower “positive potential” (where the negative potential is high) to higher positive potential.

Phase refers to the angle of rotation corresponding to the present value of emf or current. One complete circle (or rotation) corresponds to 2(pi) phase. There is a difference between current and voltage refers to this.

In describing AC, we can imagine that the current and voltage in wave form is obtained by the projection of  rotating vectors, I0 and E0. The difference in angle between these which represents the waveform obtained for E and I correctly is known as the phase difference.

(I feel that this won’t suffice. Please as more questions to clarify your point; preferable as comments to the same post)


Difference between g and G

What is the difference between capital ‘G’ and small ‘g’ in the chapter gravitation?

 g  G
 Acceleration due to gravity  Universal constant of gravitation
 varies from place to place  A constant everywhere on earth
 vector quantity  A dimensional constant
 unit is ms-2  unit is Nm2kg-2

Is potential difference is directly proptional to resistance?

Is potential difference is directly proptional to resistance? (atanu asks)

Answer:

For a constant current, the potential difference is directly proportional to the resistance included in the circuit.

For a given conductor at constant temperature, resistance is a constant and the potential difference across it is directly proportional to the current passed through it.

 

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