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In dielectric heating, if the distance between electrodes is equal to half the wavelength at a given frequency then

In dielectric heating, if the distance between electrodes is equal to half the wavelength at a given frequency then Correct Answer  the material will not be uniformly heated

Dielectric heating:

  • Dielectric heating (Capacitance heating) is the method of heating non-conductive materials.
  • The material to be heated is placed between two electrodes, to which a high-frequency energy source is connected.
  • The oscillating field passes through the material and as the field direction changes, the polarisation of individual molecules reverses rapidly, causing friction and hence heat.
  • The higher the frequency, the greater the movement.
  • Typically, frequencies in the range 5 MHz to 80 MHz are used.
  • This technology is used in Wood Gluing, RF Drying, and Plastic Welding.
  • The dielectric loss in insulators corresponds to hysteresis loss in ferromagnetic materials. This loss is due to the reversal of magnetism or magneto molecular friction. These losses are developed in a material to be heated.
  • In dielectric heating, heating is directly proportional to the frequency

 

Dielectric loss is

P = V2ωC tan δ

Where V is the applied voltage in V

f is the supply frequency in Hz

C is the capacitance

δ is the loss angle in radian

Dielectric loss is directly proportional to the frequency

In dielectric heating, if the distance between electrodes is equal to half the wavelength at a given frequency then the material will not be uniformly heated.

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