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What Steps to take when selecting a suitable sampling frequency?
The Nyquist Theorem says that the sampling frequency should be twice the bandwidth to avoid aliasing. Thus if the bandwidth of the system is bw then the sampling frequency f=2*bw.
When analog voice signal converts into digital signal the bandwidth needs 64kbps. Why?
PCM technique is used to convert analog voice signals into digital. In PCM the analog frequency is first sampled and then converted into binary bits. Each samples are taken as 8bits long. Basic communication theory requires that a minimum sampling rate of twice the frequency of the signal to be sampled will result in an accurate representation of the original signal.Human voice can have max 4000hz frequency, therefore sampling rate should be 8000 samples/sec.Which implies required bit rate for transmitting voice is 8000*8 = 64000 bits/sec = 64kbps.
When paralleling two AC generators the frequency of the incoming machine immediately prior to closing its breaker should be?
The frequency must be the same and the phase must be the same as well. This can be indicated by having a lamp connected across the switch (for each phase if 3-phase).
Why does the existence of a cutoff frequency in the photoelectric effect favor a particle theory of light rather than a wave theory?
According to the wave theory, light of any frequency can cause electrons to be ejected as long as the light is intense enough. A higher intensity corresponds to a greater electric field magnitude and more energy. Therefore, there should be no frequency below which the photoelectric effect does not occur. According to the particle theory, however, each photon carries an amount of energy that depends upon its frequency. Increasing the intensity of the light increases the number of photons but does not increase the energy of the individual photons. The cutoff frequency is that frequency at which the energy of the photon equals the work function. If the frequency of the incoming light is below the cutoff, the electrons will not be ejected because no individual photon has enough energy to impart to an electron.
What is the 60 Hz on a welder with the listed input as 208 230 volt single phase 60Hz?
60 Hertz is the frequency that the welder should be connected to, to work as it is designed to.
