Recent content by tech99

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.

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.

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...

Maybe I miss the point of this discussion, but I cannot understand how an EM wave can induce a direct current in the ionosphere. EM waves cannot have a unidirectional component. If the wave is pulsed, then Fourier tells us it is a continuous carrier modulated by the pulse waveform.

I think this phenomenon will occur with any wave, such as sound. The small diameter wavefront seen at optical frequencies may be considered as arising from the superimposition of wavelets from an infinitely wide wavefront. This is Huygens' Principle at work. If you now travel along the beam, the...

Another interesting case is the bottom point of a train wheel, which is travelling backwards.

As a radio engineer, it seems to me to resemble some behaviour which was well known by 1910. If we have two resonant circuits of the same frequency that are coupled together closely, then if we apply an initial impulse, damped oscillation will occur at one of two frequencies at random.

Heeling is caused by the couple created by the sideways force of the sails and the opposing sideways lift of the keel. Heeling is opposed by righting moments caused by the weight of the keel and bouyancy.

May I mention again that the leeway angle is equal to the angle of attack of the keel. It is important that the area of the foil is great enough so that the angle of attack at which it operates is small, such as 5 degrees. At small angles the cross section of the foil is not so important because...

For a column in compression, according to Euler's formula, the buckling strength is not sensitive to the yield strength of the material but does depend on the stiffness (modulus of elasticity).

Maybe first consider the function of a fin (or centreboard on a small craft). The sail is a aerofoil in the wind and a fin is an aerofoil in the water. The wind force on the sail may be resolved into two components: one in the forward direction, causing propulsion, and the other at right...

How are you going to measure potential difference without introducing electrons into the process?

If I place an electric circuit, containing a suitable indicator, in the path of an EM wave I can notice a current being created.

The black stains might be silver halides, in which case sodium thiosulfate will dissolve them. As silver is very toxic, to both people and the environment, be careful not to bring contaminated items into a kitchen.