can you explain it for me?
2006-07-30 01:20:48 · 5 answers · asked by star 1 in Science & Mathematics ➔ Physics
Static electricity can be interesting, amusing, or annoying, but it has few uses. But the principles behind it are the same as the electricity that homes use every day.
Long ago scientists asked a few questions.
* What makes the electrons move?
* What hidden force drives the electrons from a rug to a person and then to a metal door knob?
Scientists use the term electro-motive force (EMF) to describe the invisible force that seems to push electricity. They noticed that there are several ways to create this mysterious force.
2006-07-30 01:28:52 · answer #1 · answered by Arshat 2 · 0⤊ 0⤋
Normally a conductor (gas, liquid or solid) is neutral.
Consider a conductor ‘A......B’.
If there exists a mechanism, so that all or most of the electrons (or negative charges) are moved to the end B and further it prevents any flow of electrons from B to A internally, then there will be a constant POTENTIAL DIFFERENCE between the ends A and B.
The ‘force’ (potential difference) which prevents the electrons to move from B to A, but always makes them to move from A to B is called Electro motive force.
If we connect the points A and B externally by another conductor, then electrons from B will move to A externally.
As soon as they reach B, the mechanism removes the electrons from A and deposits on B.
Thus there will be a continuous current in the circuit.
In a cell or battery the mechanism producing emf is due to the chemicals present inside the cell.
If the ends of a conductor are maintained at different temperatures, a thermo- emf is produced between the ends of the conductor.
If conductor is moved in a magnetic field, electrons flow to one or other side, producing an emf.
When a circuit is made on or off, the collapsing magnetic field produces an emf opposing the growth or decay of the current.
2006-07-30 04:41:22 · answer #2 · answered by Pearlsawme 7 · 0⤊ 0⤋
EMF is a name for the difference in electric potential between two points. It is a measure of the amount of work you would need to do on an electron to move it between those points. It is a path integral of electric field strength times distance, and is the same over all paths between the two points. It is measured in volts. You can also view a voltage source (say, a 6 volt battery) as the potential to force an electron between those two points, through a resistance. A 12 volt battery has twice the potential to force electrons through resistance, so it would cause twice the current flow through the same resistance. All practical voltage sources are limited in their capacity to provide a current through a resistance. Reducing the resistance increases the current until the current is near the maximum the source is capable of providing. A battery has its own internal resistance, and the chemical reaction powering it can support an electron stream of limited size.
2016-03-27 07:00:59 · answer #3 · answered by Anonymous · 0⤊ 0⤋
basically it's a misnomer.
it is not at all a force it is a cause for flow of current.it is the actual ability of the cell to establish current,
it defines the strength of the current.
as height of a water tank decides the rate of flow(strength) of water EMF decides the strength of current,
even if u don't get my example,just think the effect if height is lowered & increased and relate it to EMF.
i hope u got it.
2006-07-30 01:35:25 · answer #4 · answered by uttam 1 · 0⤊ 0⤋
Voltage plus back E.M.F. .
2006-07-30 01:24:19 · answer #5 · answered by loopy 1 · 0⤊ 0⤋