Recent content by tech99

  1. tech99

    High School What Medium Does Light Travel Through in Space?

    Maxwell noticed that the "cgs" units of permittivity and permeability were related by a number equal to the speed of light. So that the electric force between two charges would be related to the magnetic force between the two charges when moving by a factor equal to c. This seems to me to be...
  2. tech99

    High School Conclusions from Thomson’s cathode ray tube experiment

    It seems that they did know that charge flowed in a circuit. Thompson himself tries to measure charge by the time it takes to accumulate on a capacitor. When they experimented with electricity passing through gases, Thompson supposed that charge was being carried by corpusles, but it was not...
  3. tech99

    Great circle between two points on the Earth's surface

    Not sure here but are you assuming that latitude is a great circle?
  4. tech99

    High School Why the bottom of a rolling wheel has zero velocity

    Is this definition universal, so it will hold if the wheel has a flange protruding below the contact surface, as on a train?
  5. tech99

    Undergrad Radiation in classical and quantum mechanics

    I suppose in a simple way that if we accelerate a charge using an alternating electric field, the radiated energy will, as always, be in quanta and the energy of each of these quanta will depend on the frequency of the alternating field.
  6. tech99

    Undergrad Mass-and-spring model of parametric amplification

    If the signal and pump are both applied to the mass, then the deflections will add. But to produce parametric action the spring stiffness must chnage with deflection. This is what you are proposing, sounds correct. I think the pump needs to be large compared with the signal.
  7. tech99

    Copper piping and cathodic protection?

    I suspect that providing cathodic protection to the interior of pipes is problematic, because the current will tend to flow locally, close to the zinc electrode. I am wondering if the discolouration of the copper you are seeing is dead algae and bacteria rather than a chemical action. It might...
  8. tech99

    Copper piping and cathodic protection?

    I would be concerned about the toxicity of zinc.
  9. tech99

    Why does the base of the stapes (oval window) have a lower amplitude in the middle ear?

    I saw your question and do not know how to reply directly to you. The lever arrangement appears to give a step down in amplitude from the tympanum to the oval window. A step down in amplitude is accompanied by a step up in force, because energy is force x distance, so remains the same.
  10. tech99

    Limitations of the CQMI method to assess causality of s-parameters

    I think the underlying issue you have is that you need to undo the embedded test fixture parameters from your overall measured s-parameters. As s-parameters relate to power, not voltage, if the test fixture is not 50 Ohms then assumprtions about voltages will be incorrect.
  11. tech99

    Why does the base of the stapes (oval window) have a lower amplitude in the middle ear?

    You ask about pressure or force at the oval window. In a fluid we have pressure and in a system of levers we have force. In hydraulics, to create a given pressure in the fluid, a smaller piston travels further but requires less force. It seems to me that the mechanism is as follows. We start...
  12. tech99

    Engineering Voltage across inductor is somehow negative despite diodes?

    An inductor has a property of inertia, analogous to a mass. So when we try to alter the conditions, it will oppose the change. If we try to reduce the current in the inductor, it will create a forward voltage to try and keep the current flowing. You ask how an inductor can have a negative...
  13. tech99

    Undergrad The effect of a radio wave on an electron

    Yes I agree with that but the initial question seems to be about just the effect of an EM wave on an electron in a plasma and does not include Earth's magnetic field.
  14. tech99

    Undergrad The effect of a radio wave on an electron

    Yes agree. Disregarding Earth's magnetic field, I think the electron in the ionosphere will have simple harmonic motion which is greater as the frequency becomes lower.
  15. tech99

    Undergrad The effect of a radio wave on an electron

    This is my simple thinking on the topic. If I consider the ionosphere as a conductor, then neglecting Earth's magnetic field, the electrons will have the same motion, though smaller, as those in the transmitting antenna. The latter does not have a DC component. The EM wave can have...