Consider a rectangular waveguide of internal dimensions 8 cm × 4 cm. assuming an H10 mode of propagation the critical wavelength would be

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ESE Electronics 2012 Paper 1: Official Paper
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  1. 8 cm
  2. 16 cm
  3. 4 cm
  4. 32 cm

Answer (Detailed Solution Below)

Option 2 : 16 cm
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ST 1: UPSC ESE (IES) Civil - Building Materials
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Detailed Solution

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Concept:

The cut-off frequency for a rectangular waveguide with dimension ‘a (length)’ and ‘b (width)’ is given as:

'm' and 'n' represents the possible modes.

The cut-off/critical wavelength is given as:

Calculation:

Given: a = 8 cm, b = 4 cm

For H10 mode

i.e. m = 1 and n = 0, we get

λC = 2 × 8 cm = 16 cm

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