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September 21, 2025, 05:47:57 am
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Author Topic: Is this adequate?  (Read 1031 times)  Share 

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dejan91

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Is this adequate?
« on: November 10, 2009, 06:30:32 pm »
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Is this an adequate explanation? VCAA 2007:



When the switch is closed, a magnetic field is momentarily induced within the soft iron core. The soft iron core will have a North Pole to the left and a south pole to the right.
Hence, there is a change in flux in the coil to the right from South to North momentarily. A voltage is induced in such a way that the flux created by the current opposes the change in flux that created it.
Thus, the current will flow from Y to X.


The assessors report said 'students were firstly expected to state Lenz's Law"
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appianway

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Re: Is this adequate?
« Reply #1 on: November 10, 2009, 06:32:01 pm »
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You've talked about opposing the change, so it shouldn't matter.
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dejan91

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Re: Is this adequate?
« Reply #2 on: November 10, 2009, 06:56:19 pm »
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Another question:

What's the difference between stopping voltage and the work function? I always get these two confused.
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arthurk

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Re: Is this adequate?
« Reply #3 on: November 10, 2009, 07:00:24 pm »
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Stopping voltage can be thought of as the energy needed to stop the electrons from reaching the other side or otherwise known as ekmax or maximum energy of the photoelectron
Work function is the energy required to eject the electron from the material

stopping voltage = photon energy - work function
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naved_s9994

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Re: Is this adequate?
« Reply #4 on: November 10, 2009, 07:08:16 pm »
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Quote from: dejan91 on November 10, 2009, 06:30:32 pm
Is this an adequate explanation? VCAA 2007:

(Image removed from quote.)

When the switch is closed, a magnetic field is momentarily induced within the soft iron core. The soft iron core will have a North Pole to the left and a south pole to the right.
Hence, there is a change in flux in the coil to the right from South to North momentarily. A voltage is induced in such a way that the flux created by the current opposes the change in flux that created it.
Thus, the current will flow from Y to X.


The assessors report said 'students were firstly expected to state Lenz's Law"

By Lenz’s Law, the direction of the current is such that its magnetic field opposes the change in magnetic flux (1) and so its magnetic field points to the right (1).  To produce this magnetic field the current needs to flow down the front of the coils and so go from Y to X.
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kamil9876

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Re: Is this adequate?
« Reply #5 on: November 10, 2009, 07:50:36 pm »
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Quote from: arthurk on November 10, 2009, 07:00:24 pm


charge* stopping voltage = photon energy - work function

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