Hi all, I have been doing a bit of browsing the net and come accross something I need to understand. Faradays Law.
I have been on several websites regarding this, and I am a little lost on the information provided.
I am far from a mathematician or science guy, so any explanitions in extremely basic (almost retarded, lol) way please.
I think I understand what the different bits of it are, the main thing I want to know is how to actually calculate the 'B' and the 'A'. Im guessing that for 'A' you would simply use the formula for calculating the area of a cylinder? But the 'B' bit has really got me.
I notice that magnets are classed in 'Nx' (N41, N35, etc). So not really sure how I would translate that into the 'B' part?
Also one final thing, what is that little triangle thing for? I read it was for the 'change in'. Again, not sure how to do that.
If anyone could provide some extremely simply put information I would appreciate it.
Thanks
CKS
Hi CKS,
Since no one better qualified has replied to your question yet I think I'll have a go at it.
I have found a website that gives some good basic information about Faraday's Law:
http://hyperphysics.phy-astr.gsu.edu/hbase...ric/farlaw.html
The site has an accompanying diagram:
Consider the image in the lower right. It is a diagram of a coil turning in a region containing a magnetic field that is constant in its strength where the coil turns.
It is the capital Greek letter delta. In a mathematical formula it denotes "a change in" a particular quantity or value.
For example, the delta t in the denominator of Faraday's formula represents "the change in time" during which the measurement of voltage is being made. If it took one tenth of a second for the coil to turn in the indicated region, then the delta t value would be 0.1.
The delta BA on the numerator of the Faraday formula represents "the change in" the product of B (the magnetic field strength) and A (the area extended by the coil). In this example the value of B remains constant, whereas, the value of A changes from zero to the area over which the coil spans for every quarter turn of the coil in the region of the field. A is the magnitude of the area that is perpendicular to the direction of the field, so while it is at a maximum when the coil is vertical in the diagram, it is at a minimum when the coil is horizontal in the diagram. (The field lines to which the area is perpendicular to run from left to right, i.e., from N to S in the diagram.)
In this example B is constant (the region through which the coil turns has constant magnetic flux) while the magnitude of the area presented perpendicular to the field changes periodically from a maximum when the coil is vertical in the diagram to a minimum of zero when the coil is parallel to the field (horizontal in the diagram).
Thus delta BA is actually B * delta A in this example. A is the only factor which changes. The change in A is greatest when the coil is horizontal thereby presenting the mimimum area perpendicular to the field and it is then that the voltage is -0.8 volts as indicated in the diagram. The voltage varies in a sinusoidal way being the highest when the coil is horizontal and the lowest when the coil is vertical. Even though the magnitude of the area perpendicular to the field is least when the coil is horizontal the magnitude of the change in A (and therefore BA) is greatest then and so the voltage is greatest at that point (greatest in magnitude although negative in value).
When the coil moves from it's horizontal position after the first quarter turn from vertical to horizontal it then moves toward the vertical position again and the voltage drops to zero once more. Moving to the horizontal position in the next quarter turn the voltage becomes +0.8 volts and then drops to zero once vertical completing a full turn.
It is the capital Greek letter delta. In a mathematical formula it denotes "a change in" a particular quantity or value.
For example, the delta t in the denominator of Faraday's formula represents "the change in time" during which the measurement of voltage is being made. If it took one tenth of a second for the coil to turn in the indicated region, then the delta t value would be 0.1.
The delta BA on the numerator of the Faraday formula represents "the change in" the product of B (the magnetic field strength) and A (the area extended by the coil). In this example the value of B remains constant, whereas, the value of A changes from zero to the area over which the coil spans for every quarter turn of the coil in the region of the field. A is the magnitude of the area that is perpendicular to the direction of the field, so while it is at a maximum when the coil is vertical in the diagram, it is at a minimum when the coil is horizontal in the diagram. (The field lines to which the area is perpendicular to run from left to right, i.e., from N to S in the diagram.)
In this example B is constant (the region through which the coil turns has constant magnetic flux) while the magnitude of the area presented perpendicular to the field changes periodically from a maximum when the coil is vertical in the diagram to a minimum of zero when the coil is parallel to the field (horizontal in the diagram).
Thus delta BA is actually B * delta A in this example. A is the only factor which changes. The change in A is greatest when the coil is horizontal thereby presenting the mimimum area perpendicular to the field and it is then that the voltage is -0.8 volts as indicated in the diagram. The voltage varies in a sinusoidal way being the highest when the coil is horizontal and the lowest when the coil is vertical. Even though the magnitude of the area perpendicular to the field is least when the coil is horizontal the magnitude of the change in A (and therefore BA) is greatest then and so the voltage is greatest at that point (greatest in magnitude although negative in value).
When the coil moves from it's horizontal position after the first quarter turn from vertical to horizontal it then moves toward the vertical position again and the voltage drops to zero once more. Moving to the horizontal position in the next quarter turn the voltage becomes +0.8 volts and then drops to zero once vertical completing a full turn.
...the main thing I want to know is how to actually calculate the 'B'
In an experimental setup like the one here indicated it is actually easiest to calculate B by measuring the area of the coil and the voltage generated and then solving for B in Faraday's equation. You can then change the parameters of the setup (the number of turns and the area of the coil) and continue using the value of B calculated earlier.
The 'x' in the 'Nx' class represents a relative strength value for Neodymium magnets.
http://www.whatareneodymiummagnets.com/faqs.html
The actual value of B for a particular magnet depends upon the geometry of the experimental seup. And that as I have indicated is most easily determined using the Faraday formula and solving for B as indicated.
Any questions?
Namaste,
-- Charles
Since no one better qualified has replied to your question yet I think I'll have a go at it.
I have found a website that gives some good basic information about Faraday's Law:
http://hyperphysics.phy-astr.gsu.edu/hbase...ric/farlaw.html
The site has an accompanying diagram:
Consider the image in the lower right. It is a diagram of a coil turning in a region containing a magnetic field that is constant in its strength where the coil turns.
QUOTE
...what is that little triangle thing for?
It is the capital Greek letter delta. In a mathematical formula it denotes "a change in" a particular quantity or value.
For example, the delta t in the denominator of Faraday's formula represents "the change in time" during which the measurement of voltage is being made. If it took one tenth of a second for the coil to turn in the indicated region, then the delta t value would be 0.1.
The delta BA on the numerator of the Faraday formula represents "the change in" the product of B (the magnetic field strength) and A (the area extended by the coil). In this example the value of B remains constant, whereas, the value of A changes from zero to the area over which the coil spans for every quarter turn of the coil in the region of the field. A is the magnitude of the area that is perpendicular to the direction of the field, so while it is at a maximum when the coil is vertical in the diagram, it is at a minimum when the coil is horizontal in the diagram. (The field lines to which the area is perpendicular to run from left to right, i.e., from N to S in the diagram.)
In this example B is constant (the region through which the coil turns has constant magnetic flux) while the magnitude of the area presented perpendicular to the field changes periodically from a maximum when the coil is vertical in the diagram to a minimum of zero when the coil is parallel to the field (horizontal in the diagram).
Thus delta BA is actually B * delta A in this example. A is the only factor which changes. The change in A is greatest when the coil is horizontal thereby presenting the mimimum area perpendicular to the field and it is then that the voltage is -0.8 volts as indicated in the diagram. The voltage varies in a sinusoidal way being the highest when the coil is horizontal and the lowest when the coil is vertical. Even though the magnitude of the area perpendicular to the field is least when the coil is horizontal the magnitude of the change in A (and therefore BA) is greatest then and so the voltage is greatest at that point (greatest in magnitude although negative in value).
When the coil moves from it's horizontal position after the first quarter turn from vertical to horizontal it then moves toward the vertical position again and the voltage drops to zero once more. Moving to the horizontal position in the next quarter turn the voltage becomes +0.8 volts and then drops to zero once vertical completing a full turn.
QUOTE (->
| QUOTE |
| ...what is that little triangle thing for? |
It is the capital Greek letter delta. In a mathematical formula it denotes "a change in" a particular quantity or value.
For example, the delta t in the denominator of Faraday's formula represents "the change in time" during which the measurement of voltage is being made. If it took one tenth of a second for the coil to turn in the indicated region, then the delta t value would be 0.1.
The delta BA on the numerator of the Faraday formula represents "the change in" the product of B (the magnetic field strength) and A (the area extended by the coil). In this example the value of B remains constant, whereas, the value of A changes from zero to the area over which the coil spans for every quarter turn of the coil in the region of the field. A is the magnitude of the area that is perpendicular to the direction of the field, so while it is at a maximum when the coil is vertical in the diagram, it is at a minimum when the coil is horizontal in the diagram. (The field lines to which the area is perpendicular to run from left to right, i.e., from N to S in the diagram.)
In this example B is constant (the region through which the coil turns has constant magnetic flux) while the magnitude of the area presented perpendicular to the field changes periodically from a maximum when the coil is vertical in the diagram to a minimum of zero when the coil is parallel to the field (horizontal in the diagram).
Thus delta BA is actually B * delta A in this example. A is the only factor which changes. The change in A is greatest when the coil is horizontal thereby presenting the mimimum area perpendicular to the field and it is then that the voltage is -0.8 volts as indicated in the diagram. The voltage varies in a sinusoidal way being the highest when the coil is horizontal and the lowest when the coil is vertical. Even though the magnitude of the area perpendicular to the field is least when the coil is horizontal the magnitude of the change in A (and therefore BA) is greatest then and so the voltage is greatest at that point (greatest in magnitude although negative in value).
When the coil moves from it's horizontal position after the first quarter turn from vertical to horizontal it then moves toward the vertical position again and the voltage drops to zero once more. Moving to the horizontal position in the next quarter turn the voltage becomes +0.8 volts and then drops to zero once vertical completing a full turn.
...the main thing I want to know is how to actually calculate the 'B'
In an experimental setup like the one here indicated it is actually easiest to calculate B by measuring the area of the coil and the voltage generated and then solving for B in Faraday's equation. You can then change the parameters of the setup (the number of turns and the area of the coil) and continue using the value of B calculated earlier.
QUOTE
I notice that magnets are classed in 'Nx' (N41, N35, etc). So not really sure how I would translate that into the 'B' part?
The 'x' in the 'Nx' class represents a relative strength value for Neodymium magnets.
http://www.whatareneodymiummagnets.com/faqs.html
The actual value of B for a particular magnet depends upon the geometry of the experimental seup. And that as I have indicated is most easily determined using the Faraday formula and solving for B as indicated.
Any questions?
Namaste,
-- Charles
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