MCQOPTIONS
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MCQOPTIONS
This section includes 1085 Mcqs, each offering curated multiple-choice questions to sharpen your Electronics & Communication Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 301. |
A capacitance of 100 f if is connected in series with a resistance of 8000 £2. The time constant of the circuit is |
| A. | 0.2 s |
| B. | 0.4 |
| C. | 0.6 s |
| D. | 0.8 s |
| Answer» E. | |
| 302. |
Emf is closed __________ integral of non-conservational electric fieldthat is generated by battery. |
| A. | Line |
| B. | Surface |
| C. | Volume |
| D. | None of these |
| Answer» B. Surface | |
| 303. |
Wave attenuation is given as ______________. |
| A. | e+βx |
| B. | e-βx |
| C. | e+αx |
| D. | e−αx |
| Answer» E. | |
| 304. |
Reflection coefficient Γ is __________. |
| A. | ≥100 |
| B. | 0 |
| C. | ≤ 1 |
| D. | None of these |
| Answer» D. None of these | |
| 305. |
A family of arcs is obtained in the Smith chart by varying normalized reactance in a range of __________. |
| A. | −1 to 0 |
| B. | 0 to 1 |
| C. | 0 to ∞ |
| D. | −∞ to ∞ |
| Answer» E. | |
| 306. |
Conductivity of dielectric is _________. |
| A. | low |
| B. | high |
| C. | both (a) and (b) |
| D. | cannot say |
| Answer» B. high | |
| 307. |
__________ are caused by accelerated charges |
| A. | Time-varying fields |
| B. | Waves |
| C. | Both (a) and (b) |
| D. | None of these |
| Answer» D. None of these | |
| 308. |
If three 15 uf capacitors are connected in series , the net capacitanceis |
| A. | 5uf |
| B. | 30 Ue |
| C. | 40 uF |
| D. | 50 UF |
| Answer» B. 30 Ue | |
| 309. |
Which of the following capacitors can be used for temperaturecompensation ? |
| A. | Air capacitor |
| B. | Ceramic capacitor |
| C. | Paper capacitor |
| D. | None of the above |
| Answer» C. Paper capacitor | |
| 310. |
Which of the following expression is correct for electric field strength? |
| A. | E = D/E |
| B. | E = D2/t |
| C. | E = jtD |
| D. | E = nD2 |
| Answer» B. E = D2/t | |
| 311. |
Divergence of a vector at a point in a vector field is __________quantity. |
| A. | vector |
| B. | scalar |
| C. | both (a) an (b) |
| D. | none of these |
| Answer» C. both (a) an (b) | |
| 312. |
In the case of lossy capacitor, its series equivalent resistance value will be |
| A. | Small |
| B. | Very small |
| C. | Large |
| D. | Zero |
| Answer» C. Large | |
| 313. |
For transformation from the Cartesian coordinate system toSpherical coordinate system, ap should be equal to ____________. |
| A. | cos θ |
| B. | − cos θ |
| C. | sin θ |
| D. | − sin θ |
| Answer» B. − cos θ | |
| 314. |
Antenna bandwidth can be increased by using__________. |
| A. | A feed horn |
| B. | Thicker wires |
| C. | Cages |
| D. | All of these |
| Answer» E. | |
| 315. |
Magnetic susceptibility is _________. |
| A. | unitless |
| B. | dimensionless |
| C. | both (a) and (b) |
| D. | none of these |
| Answer» C. both (a) and (b) | |
| 316. |
While testing a capacitor with ohm-metre, if the capacitor shows charging, but the final resistance reading is appreciably less than normal, it can be concluded that the capacitor is |
| A. | short-circuited |
| B. | open circuited |
| C. | alright |
| D. | leaky |
| Answer» E. | |
| 317. |
Which of the following materials has the highest value of dielectricconstant? |
| A. | Glass |
| B. | Vacuum |
| C. | Ceramics |
| D. | Oil |
| Answer» D. Oil | |
| 318. |
In a Spherical coordinate system, φ is ____________. |
| A. | angle of elevation |
| B. | azimuthal angle |
| C. | distant from the origin to the point |
| D. | all of these |
| Answer» C. distant from the origin to the point | |
| 319. |
is that property of a capacitor which delays any change of voltageacross it. |
| A. | Inductance |
| B. | Capacitance |
| C. | Potential gradient |
| D. | None of the above |
| Answer» C. Potential gradient | |
| 320. |
Cavity is a rectangular wave guide _______. |
| A. | Open at both ends |
| B. | Shorted at both ends |
| C. | With one end open and the other shorted |
| D. | None of these |
| Answer» C. With one end open and the other shorted | |
| 321. |
A capacitor in a circuit became hot and ultimately exploded due to wrong con¬nections, which type of capacitor it could be ? |
| A. | Paper capacitor |
| B. | Ceramic capacitor |
| C. | Electrolytic capacitor |
| D. | Any-of the above |
| Answer» D. Any-of the above | |
| 322. |
The direction of electric dipole moment is _________ applied electric field. |
| A. | orthogonal |
| B. | contrary |
| C. | same |
| D. | none of these |
| Answer» D. none of these | |
| 323. |
Information or energy through the wave guide travels at _______velocity. |
| A. | Medium |
| B. | Phase |
| C. | Group |
| D. | None of these |
| Answer» D. None of these | |
| 324. |
In__________array, radiation is in the same direction as the arrayorientation. |
| A. | Broadside |
| B. | End fire |
| C. | None of these |
| D. | Cannot say |
| Answer» E. | |
| 325. |
An open wire transmission line having a characteristic impedance of 600 ohms is terminated by a resistive load of 900 Ω. The standing wave ratio will be |
| A. | 1.5 |
| B. | 2.5 |
| C. | 3.5 |
| D. | 4.5 |
| Answer» B. 2.5 | |
| 326. |
The directivity of 20 turn helix having a = 12° circumference equal to one wavelength, will be |
| A. | 1.8 dB |
| B. | 6 dB |
| C. | 12 dB |
| D. | 18 dB |
| Answer» E. | |
| 327. |
An antenna has 40 Ω resistance and 60 Ω radiation resistance. The efficiency of the antenna is |
| A. | 30% |
| B. | 40% |
| C. | 50% |
| D. | 60% |
| Answer» E. | |
| 328. |
The effective length of an λ/2 antenna (Given Rr = 73 Ω and (Ae)max = 0.13 λ2 and η = 120 p is __________ . |
| A. | 0.6348 λ |
| B. | 0.317 λ |
| C. | 0.158 λ |
| D. | 0.371 λ |
| Answer» C. 0.158 λ | |
| 329. |
A dipole antenna of λ/8 length has an equivalent total loss resistance of 1.5 Ω. The efficiency of the antenna is |
| A. | 0.89159% |
| B. | 8.9159% |
| C. | 89.159% |
| D. | 891.59% |
| Answer» D. 891.59% | |
| 330. |
Given that , if the radiation intensity of an antenna is proportional to sin2 θ, where θ is the elevation angle, the antenna directivity will be |
| A. | [A]. |
| B. | [B]. |
| C. | [C]. |
| D. | [D]. |
| Answer» E. | |
| 331. |
Two identical antennas are placed in the θ = p/2 plane as shown in the figure. The elements have equal amplitude excitation with 180° polarity difference, operating of the far-zone resultant electric field strength normalized with that of a single element, both computed for φ = 0, is |
| A. | [A]. |
| B. | [B]. |
| C. | [C]. |
| D. | [D]. |
| Answer» E. | |
| 332. |
Antenna efficiency of antenna is, if radiation resistance is 370 Ω and loss resistance is 100 Ω |
| A. | 80% |
| B. | 87% |
| C. | 78% |
| D. | 21.27% |
| Answer» D. 21.27% | |
| 333. |
∇2 is |
| A. | vector |
| B. | scalar |
| C. | depend on direction |
| D. | none |
| Answer» C. depend on direction | |
| 334. |
A λ/8 section of transmission line is determined of load impedance of (2 - j 5) Ω. If characteristic impedance of line is 10 Ω. Then input impedance of line is |
| A. | 10 Ω |
| B. | (6.9 + j 7.24) Ω |
| C. | (1.75 + j 3.098) Ω |
| D. | (2 - j 5) Ω |
| Answer» D. (2 - j 5) Ω | |
| 335. |
A transmission line has characteristics impedance of (75 + j 0.01) Ω and is terminated in a load impedance of (70 + j 50) Ω. The reflection coefficient will be |
| A. | 0.08 + j 0.32 |
| B. | 0.32 + j 1.38 |
| C. | 0.70 - j 2.97 |
| D. | 1.1 + j 0.32 |
| Answer» B. 0.32 + j 1.38 | |
| 336. |
A transmission line has characteristics impedance of (75 + j 0.01) Ω and is terminated in a load impedance of (70 + j 50) Ω. The transmission coefficient will be |
| A. | 1.70 - j 2.97 |
| B. | 0.08 + j 0.32 |
| C. | 1.32 + j 1.38 |
| D. | 1.08 + j 0.32 |
| Answer» E. | |
| 337. |
ZL = 200 Ω and it is desired that Zi = 50 Ω The quarter wave transformer should have a characteristic impedance of |
| A. | 100 Ω |
| B. | 40 Ω |
| C. | 10000 Ω |
| D. | 4 Ω |
| Answer» B. 40 Ω | |
| 338. |
Two co-axial cylindrical sheets of charge are present in free space fs = 5 c/m2 at r = 2 m and rs = -2 c/m2 at r = 4 m, The displacement flux density at r = 3 m is |
| A. | [A]. |
| B. | [B]. |
| C. | [C]. |
| D. | [D]. |
| Answer» D. [D]. | |
| 339. |
Consider the following; for a loss-less transmission line we can write, Zin = - jz0 for a shorted line with l = λ/8Zin = ± j ∞ for a shorted line with l = λ/4Zin= jz0 for an open line with l = λ/2Zin = 0 for a matched line of any length Select the correct answer using the codes given below codes. |
| A. | 1, 2 |
| B. | 2, 3 |
| C. | 1, 3 |
| D. | 2, 4 |
| Answer» E. | |
| 340. |
The cut off wavelength λc for TE20 mode for a standard rectangles waveguide is |
| A. | 2/a |
| B. | 2a |
| C. | a |
| D. | 2a2 |
| Answer» D. 2a2 | |
| 341. |
If H = 0.1 sin (108p t + βλ) A/m for a plane wave propagating in free space, then the time average Poynting vector is |
| A. | (0.6psin2 βy) w/m2 |
| B. | - 0.6p w/m2 |
| C. | 1.2p w/m2 |
| D. | - 1.2p w/m2 |
| Answer» E. | |
| 342. |
A transmission line having 50 Ω impedance is terminated in a load of (40 + j 30) Ω. The VSWR is |
| A. | j 0.033 |
| B. | 0.8.+ j 0.6 |
| C. | 1 |
| D. | 2 |
| Answer» E. | |
| 343. |
A transmission line has primary constants R, L, G and C and secondary constant z0 and γ = (a + Jβ). If the line is loss less, then |
| A. | R = 0, G ≠ 0, and a = 0 |
| B. | R = 0, G = a, 0 and β = |r| |
| C. | G = 0, a = β |
| D. | R = 0, G = 0, a = 0, β = |r| |
| Answer» B. R = 0, G = a, 0 and β = |r| | |
| 344. |
When a plane wave is incident normally from dielectric '1' (μ0, ε1) onto dielectric '2' (μ0, ε2) the electric field of the transmitted wave is 2 times the electric field of the reflected wave. The ratio ε2/ε1 is |
| A. | 0.5 |
| B. | 1 |
| C. | 2 |
| D. | 4 |
| Answer» E. | |
| 345. |
A plane EM wave is travelling in an unbound loss less dielectric having μy = 1 and εy = 4, the time average Poynting vector of the wave is 5 W/m3 . The phase velocity vp (assuming velocity of light as 3 x 108 m/sec) is |
| A. | 1.5 x 108 m/sec |
| B. | 3 x 108 m/sec |
| C. | 2.5 x 108 m/sec |
| D. | 0.5 x 108 m/sec |
| Answer» B. 3 x 108 m/sec | |
| 346. |
The electric field of the incident wave is , where ω = 3 x 109p and β = 10 p. The electric field of the transmitted wave Et is given by |
| A. | [A]. |
| B. | [B]. |
| C. | [C]. |
| D. | [D]. |
| Answer» D. [D]. | |
| 347. |
The incidence from dielectric medium 1 (ε1) into dielectric medium 2 (ε2), Brewster angle θB and the corresponding angle of transmission θt for will be respectively |
| A. | 30° and 30° |
| B. | 30° and 60° |
| C. | 60° and 30° |
| D. | 30° and 60° |
| Answer» D. 30° and 60° | |
| 348. |
A transmission line of characteristic impedance z0 = 50 Ω. Phase Velocity = 2 x 108 m/sec, and length l = 1 m is terminated by a load z1 = (30 - j 40) ohms. The input impedance of the line for a frequency of 100 MHz will be |
| A. | (30 + j x 40) Ω |
| B. | (30 - j 40) Ω |
| C. | (50 + j x 40) Ω |
| D. | (50 - j 40) Ω |
| Answer» C. (50 + j x 40) Ω | |
| 349. |
A medium is divided into regions I and II about x = 0 plane, as shown in the figure below. An EM wave with electric field is incident normally on the interface from region-I. The electric field E2 in region-II at the interface is |
| A. | E2 = E1 |
| B. | [B]. |
| C. | [C]. |
| D. | [D]. |
| Answer» D. [D]. | |
| 350. |
Voltage standing wave pattern in a loss less transmission line with characteristic impedance 50 Ω and a resistive load is shown in the figure. Reflection coefficient is given by |
| A. | -0.6 |
| B. | -1 |
| C. | 0.6 |
| D. | 0 |
| Answer» D. 0 | |