In a circular waveguide the dominant mode is TE01 TE11 TE20 TE21 Some applicatio

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Question
In a circular waveguide the dominant mode is
Options
A. TE₀₁
B. TE₁₁
C. TE₂₀
D. TE₂₁

Correct Answer

TE₁₁

Explanation

Some applications require dual polarization capability. Circular waveguide has this capability.

These analysis uses cylindrical coordinates.

In circular waveguide TE₁₁ mode has the lowest cut off frequency and is the dominant mode.

If D is diameter of waveguide

?_c = 1.706 D for TE₁₁ mode

?_c = 1.029 D for TE₂₁ mode

?_c = 0.82 D for TE₀₁ mode

?_c = 1.306 D for TM₀₁ mode.

More questions

1. An RC snubber circuit is used to protect a thyristor against :
Options
A. false triggering
B. failure to turn on
C. switching transients
D. failure to commutate

2. The displacement flux density at a point on the surface of a perfect conductor is = 2(a_x - 3 a_z)c/m² pointing away from the surface. The charge density at that point c/m² will be
Options
A. 2
B. - 2
C. 4
D. - 4

3. To increase Q factor of a coil, the wire should be
Options
A. long
B. thin
C. thick
D. long and thin

4. Match the following:

	List I (DOS commands)		List II (Meaning)
A.	ATTRIB	1.	Displays all directories and subdirectories
B.	SCAN DISK	2.	Moves files to another director
C.	MOVE	3.	Checks the status of disc
D.	TREE	4.	Hides a file

Options
A. A-1, B-2, C-3, D-4
B. A-3, B-4, C-2, D-1
C. A-2, B-3, C-4, D-1
D. A-4, B-3, C-2, D-1

5. Match the following:

	List I		List II
A.	SSB Modulation	1.	Transmission line
B.	? . B = 0	2.	Hilbert transform
C.	Model dispersion	3.	Faraday's law
		4.	Absence of magnetic monopoles
		5.	Waveguides
		6.	Phase locked loop

Options
A. A-1, B-3, C-5
B. A-5, B-4, C-2
C. A-6, B-4, C-5
D. A-2, B-4, C-5

6. Match the following:

	List I		List II
A.	(? x E)ds = 0	1.	Continuity equation
B.	rv.dv = Q	2.	Ampere's law
C.	(J + D)ds	3.	Gauss law
D.	-r_vdv	4.	Faraday's law
E.	H.dl = (? x H)ds	5.	Stoke's theorem

Options
A. A-4, B-3, C-2, D-1, E-5
B. A-1, B-2, C-3, D-4, E-5
C. A-4, B-2, C-1, D-3, E-5
D. A-1, B-5, C-4, D-2, E-3

7. Match the following:

	List I (Command in WORD)		List II (Meaning)
A.	END	1.	The bar displays the current position of cursor
B.	HOME	2.	Moves cursor to the beginning of current line
C.	Status	3.	Moves cursor to end of document

Options
A. A-1, B-2, C-3
B. A-3, B-1, C-2
C. A-2, B-3, C-1
D. A-3, B-2, C-1

8. Match the following:

	List I		List II
A.	Penetration frequency	1.	Lowest frequency at which charged particles spiral in fixed magnetic field
B.	Optimum working frequency	2.	Same as critical and frequency
C.	Gyro frequency	3.	Highest frequency of radio waves that can be used
D.	Maximum usable frequency	4.	The most effective frequency for ionosphere propagation of radio waves

Options
A. A-2, B-4, C-1, D-3
B. A-4, B-1, C-3, D-2
C. A-1, B-3, C-2, D-4

9. Match the following:

	List I		List II
A.	Output of signal generator	1.	Modulated
B.	Error signal from a synchro	2.	Digital
C.	Output of a JK flip flop	3.	Analog
D.	Signal received by radar	4.	Stoichastic

Options
A. A-1, B-3, C-2, D-4
B. A-3, B-1, C-2, D-4
C. A-3, B-1, C-4, D-2
D. A-1, B-3, C-4, D-2

10. Match the following:

	List I		List II
A.	TV	1.	1 kHz
B.	Radio	2.	3 kHz
C.	Telephony	3.	9 kHz
D.	Telegraphy	4.	5 MHz

Options
A. A-4, B-1, C-2
B. A-4, B-3, C-2
C. A-2, B-1, C-3
D. A-1, B-2, C-3

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