shc25
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Electricity Practical
Our teacher has told us that we will being doing an electricity practical task where the notion of "y = mx + b" will be used. (i.e. our graph will
have a non-(0,0) intercept). Does anyone have any idea of what this might be? Thanks!
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Brain&Force
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Photoelectric effect?
E = hf - φ where E is the maximum kinectic energy of an electron, h is the Planck constant, f is the frequency of incident light, and φ is the work
function of the metal.
At the end of the day, simulating atoms doesn't beat working with the real things...
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aga
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Ohm's Law i think.
a plot of current vs voltage will be a straight line for a 'normal' fixed resistor, and bent or wiggly for a non-ohmic resistor (one that changes
resistance in reponse to voltage or current).
This may help:-
http://www2.cose.isu.edu/~hackmart/ohm%27s%20law_101l.pdf
Edit: Seems y = mx + b is just the formula for a straight line graph.
[Edited on 15-6-2014 by aga]
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smaerd
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Could be practically anything. Typically electrical phenomena do not follow perfectly linear equations. Exponential, and sinuisoidal/harmonic
equations seem significantly more common. However, for approximation purposes linear type analysis seems possible.
Photo-electric effect would be one of those things that works as B&F stated.
All kinds of sensors can produce a linear region between two variables. One example currently on my mind would be current verses irradiation of PIN
photodiodes.
Realistically though, a professor could ask anything, "Say the flux of a magnetic field of 5T 4 M away from a 20 turn solenoid that has a surface area
of 20cm^2 follows the equation dPsy/dt = 35x + 12, what is the electricpotential across the solenoid?". etc. Probably better off asking the professor.
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aga
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If you just mean the algebra part, then it means 'a straight line' if you draw a graph.
y = something times x plus a bit.
If the 'bit' (b) is not zero, then you'll not get a result where x=0 and y=0, i.e. a '0,0 intercept', so long as b is not 0.
That pdf looks like a class handout ...
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woelen
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The ohmic law is not a good example of y=mx + b, for b not equal to 0. Every passive resistor, being linear or not has a characteristic, which can be
written as V = R(I), where R is a function of the current I, with the property R(0) = 0. It is not necessarily true that R(-I) = -R(I), e.g. think of
a diode. For a linear resistor, R(I) is of the form R*I, with * being normal multiplication.
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aga
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Agreed.
The class should be on Ohm's Law and the straight line equation given in a different class.
Combining the two will just confuse the students.
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PHILOU Zrealone
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R is also R(T) when temperature increases resistivity also does and when it freezes outside the current encounters less resistance.
PH Z (PHILOU Zrealone)
"Physic is all what never works; Chemistry is all what stinks and explodes!"-"Life that deadly disease, sexually transmitted."(W.Allen)
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Artemus Gordon
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A forward-biased Silicon diode is a good example of y = mx + b. Current flow is negligible until voltage = approx. 0.6v, then it behaves Ohmically
(Resistance = m, current = x, voltage = y).
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