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  1. R

    What is ohms law (was Ic=C x dv/dt)

    Fine, we agree then. For the material to follow Ohm's law, the resistance of a material must not change if measured using different currents. Or, the resistivity of a material must not change if measured using different current densities. Ratch
  2. R

    What is ohms law (was Ic=C x dv/dt)

    An equation by itself cannot express linearity. Ohm's law requires linearity. The equation has to be analyzed to determine if it is linear. Therefore, an equation by itself cannot express Ohm's law. If resistivity can be determined by an equation, then so can conductivity, which is the...
  3. R

    What is ohms law (was Ic=C x dv/dt)

    Look at the second paragraph of the quote from Haliday & Resnick found in post #8 of this thread. They keep saying that Ohm's law is a definition of a property of a material, specifically linearity. You want it to be a method of calculation. Ratch
  4. R

    What is ohms law (was Ic=C x dv/dt)

    Look at the OP's first post again. The title of the thread was I = C dv/dt, and he asked how to obtain dv/dt. That is a differential equation question, not a steady state condition. Which is easily disproven by any picture taken of the Earth from space. Charge flows, current already means...
  5. R

    R/2R resistor ladder

    Ok, it looks like a node analysis is the way to go. Only three nodes. Ratch
  6. R

    What is ohms law (was Ic=C x dv/dt)

    If V/R is the definition of resistance, then its reciprocal is also the definition of conductivity. Conductivity is just another way of representing a property of a material. What constant would that be? Resistance is not a constant. It varies with the kind of material and the shape of the...
  7. R

    What is ohms law (was Ic=C x dv/dt)

    The resistance of a non-ohmic material has to measured at each value of current. The resistance of a ohmic material only has to be measured once. Ratch
  8. R

    What is ohms law (was Ic=C x dv/dt)

    What is that supposed to mean? And each almost straight segment has a different slope, so the whole line curves. Ratch
  9. R

    What is ohms law (was Ic=C x dv/dt)

    The discussion is past. Ohmic and non-ohmic materials are defined. It only remains to determine if a material follows Ohm's law. Ratch
  10. R

    What is ohms law (was Ic=C x dv/dt)

    Yes, he is talking about the linearity of ohmic materials like metallic wires. Those results would not be true if measurements were made on non-ohmic substances, would they? Ratch
  11. R

    R/2R resistor ladder

    Where or what is Vin? Ratch
  12. R

    What is ohms law (was Ic=C x dv/dt)

    J and E define the resistivity and therefore the conductivity. The following is from Wikipedia. Ratch
  13. R

    indicate where should be NPN and PNP transistors?

    Each diagram can show two correct transistor placements. I don't see what is weird about the emitter being drawn on top. Ratch
  14. R

    indicate where should be NPN and PNP transistors?

    Both answers would be correct. Ratch
  15. R

    What is ohms law (was Ic=C x dv/dt)

    No, that is the definition of conductivity, or the reciprocal of conductivity which is resistivity. Here is a quote from a physics book by Halliday and Resnick, 1967 p. 780 . "We stress that the relationship V = i R is not a statement of Ohm's law. A conductor obeys Ohm's law only if its V...
  16. R

    What is ohms law (was Ic=C x dv/dt)

    I should have been more clear in saying Ohm's law is a material property defined by a linear relationship between V and I, not a definition of resistance or impedance as mostly taught today. Ratch
  17. R

    indicate where should be NPN and PNP transistors?

    Looks to me like you did the problem correctly. You specified the correct type of transistor (NPN,PNP) for the voltages given, and showed the signal voltage inverted for the common emitter configuration, and no inversion for the common collector configuration. The current present in the...
  18. R

    Negative Voltage

    I wish all questions were this easy. Voltage is always measured from a reference point. If the voltage to be measured has a higher value than the reference point, the voltage is positive. Otherwise negative or zero. Voltage is not the ability to do work. That is the definition of energy...
  19. R

    What is ohms law (was Ic=C x dv/dt)

    The technicality is that Ohm's law is mostly represented and taught incorrectly as a relationship when it is really a definition. Naming something as one thing when it is really something else makes it a misnomer. Voltage and current have to be evaluated to determine if Ohm's law is being...
  20. R

    What is ohms law (was Ic=C x dv/dt)

    Reactance only applies to sinusoidal steady state. Transient behavior requires differential equations. Linear differential equations like those found in most circuits are not too bad. Good thing we don't live in Columbus's time, or you would believe the Earth is flat. Similarly, in Galileo's...
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