## Objective Questions on Waveguide

Objective Questions on Waveguide, waveguide questions, and answers, MCQ on waveguides, gate questions on the rectangular waveguides, MCQ on the rectangular and circular waveguides.

### Multiple Choice Questions

Q.1. The waves in a waveguide

- travel along the border walls of the waveguide
- are reflected from the side walls but do not travel along them
- travel through the dielectric without touching the walls
- travel along all the four walls

**Answer:** travel along the border walls of the waveguide

Q.2. Waveguides can carry

- TE mode
- TM mode
- mixed mode
- all

**Answer:** all

Q.3. The cut-off frequency of a waveguide depends on

- dimensions of the waveguide
- wave mode
- the dielectric property of the medium in the waveguide
- all

**Answer:** all

Q.4. In Rectangular Waveguide (RWG), the mode subscripts m and n indicate

- no. of half-wave patterns
- no. of full-wave patterns
- no. of the zeros of the field
- none

**Answer:** no. of half-wave patterns

Q.5. Wave impedance of waveguides in the TE mode can be

- \frac{\eta }{\sqrt{1-(\frac{\lambda }{\lambda _{0}})^{2}}}
- \eta \sqrt{1-(\frac{\lambda }{\lambda _{0}})^{2}}
- both
- none

**Answer:** \frac{\eta }{\sqrt{1-(\frac{\lambda }{\lambda _{0}})^{2}}}

Q.6. The dominant TE mode in rectangular waveguides is

- TE
_{01} - TE
_{11} - TE
_{20} - TE
_{10}

**Answer:** TE_{10}

Q.7. Cut-off wavelength of rectangular waveguides is

- \frac{2}{\sqrt{(\frac{m}{a})^{2}+(\frac{n}{b})^{2}}}
- \frac{2}{\sqrt{(\frac{m}{a})^{2}-(\frac{n}{b})^{2}}}
- both
- none

**Answer:** \frac{2}{\sqrt{(\frac{m}{a})^{2}+(\frac{n}{b})^{2}}}

Q.8. In RWG, for dominant mode, the cut-off wavelength is

- 2a
- 2b
- a
- none

**Answer:** 2a

Q.9. An air-filled rectangular waveguide has dimensions of 6 × 4 cm. Its cut-off frequency for the TE10 mode is

- 2.5 GHz
- 25 GHz
- 25 MHz
- 5 GHz

**Answer:** 2.5 GHz

Q.10. In hollow rectangular waveguides,

- the phase velocity is greater than the group velocity
- the phase velocity is greater than the velocity of light in free space
- both
- none

**Answer:** both

Q.11. The dominant mode in the circular waveguide is

- TE
_{10} - TE
_{11} - TE
_{01} - TE
_{12}

**Answer:** TE_{11}

Q.12. Nonexistent modes in circular waveguides are

- TE
_{10} - TE
_{00} - both
- none

Answer: TE_{00}

Q.13. Degenerate modes in circular waveguides are

- TE
_{01}and TM_{11} - TE
_{22}and TM_{22} - both
- none

**Answer:** TE_{01} and TM_{11}

Q.14. Theoretically, the number of modes that can exist in cylindrical waveguides are

- zero
- one
- two
- infinite

**Answer:** infinite

15. Guided wavelength of cylindrical waveguides is

- \frac{\lambda}{\sqrt{1-(\frac{\lambda}{\lambda _{0}})^{2}}}
- \frac{\lambda}{\sqrt{1-(\frac{f_{0}}{f})^{2}}}
- both
- none

**Answer:** both