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MCQOPTIONS
This section includes 9294 Mcqs, each offering curated multiple-choice questions to sharpen your Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 151. |
A parallel polarized wave is incident from air into paraffin having relative permittivity 3, the value of its Brewster angle is |
| A. | 0 |
| B. | 30 |
| C. | 45 |
| D. | 60 |
| Answer» E. | |
| 152. |
For a 400 kHz transmission line having L = 0.5 mH/km, C = 0.08 mF and negligible R and G, the value of propagation constant P will be |
| A. | 15.9 radians/km |
| B. | 31.8 radians/km |
| C. | 63.6 radians/km |
| D. | 105.4 radians/km |
| Answer» B. 31.8 radians/km | |
| 153. |
The Depth of penetration of EM wave in medium having conductivity at a frequency of 1 MHz is 25 cm. The depth of penetration at a frequency of 4 MHz will be |
| A. | 6.25 cm |
| B. | 12.50 cm |
| C. | 50 cm |
| D. | 100 cm |
| Answer» C. 50 cm | |
| 154. |
The radiation resistance of a /16 wire dipole in free space will be nearly |
| A. | 1 Ω |
| B. | 3 Ω |
| C. | 13 Ω |
| D. | 30 Ω |
| Answer» C. 13 Ω | |
| 155. |
Two identical antennas are placed in the = 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 = 0, is |
| A. | <img src="/_files/images/electronics-and-communication-engineering/electromagnetic-field-theory/203-414-2.png"> |
| B. | <img src="/_files/images/electronics-and-communication-engineering/electromagnetic-field-theory/203-414-3.png"> |
| C. | <img src="/_files/images/electronics-and-communication-engineering/electromagnetic-field-theory/203-414-4.png"> |
| D. | <img src="/_files/images/electronics-and-communication-engineering/electromagnetic-field-theory/203-414-5.png"> |
| Answer» E. | |
| 156. |
Calculate wave impedance for TE mode |
| A. | (377)Ω |
| B. | 226 Ω |
| C. | |
| D. | 629 Ω |
| Answer» E. | |
| 157. |
In a 100 turn coil, if the flux through each turn is (t3 - 2t)mWb, the magnitude of the induced emf in the coil at a time of 4 sec is |
| A. | 46 mV |
| B. | 56 mV |
| C. | 4.6 V |
| D. | 5.6 V |
| Answer» D. 5.6 V | |
| 158. |
Consider a loss less antenna with a directive gain of + 6 dB. If 1 mW of power is fed to it the total power radiated by the antenna will be |
| A. | 4 mW |
| B. | 1 mW |
| C. | 7 mW |
| D. | 1/4 mW |
| Answer» B. 1 mW | |
| 159. |
The electric field of the incident wave is , where = 3 x 109p and = 10 p. The electric field of the transmitted wave Et is given by |
| A. | <img src="/_files/images/electronics-and-communication-engineering/electromagnetic-field-theory/197-244-2.png"> |
| B. | <img src="/_files/images/electronics-and-communication-engineering/electromagnetic-field-theory/197-244-3.png"> |
| C. | <img src="/_files/images/electronics-and-communication-engineering/electromagnetic-field-theory/197-244-4.png"> |
| D. | <img src="/_files/images/electronics-and-communication-engineering/electromagnetic-field-theory/197-244-5.png"> |
| Answer» D. <img src="/_files/images/electronics-and-communication-engineering/electromagnetic-field-theory/197-244-5.png"> | |
| 160. |
Which of the following should dominant wave have? |
| A. | Lowest cut off frequency |
| B. | Highest cut off frequency |
| C. | No attenuation |
| D. | No phase shift |
| Answer» B. Highest cut off frequency | |
| 161. |
A (75 - j 40) W load is connected to a co-axial line of z0 = 75 at 6 MHz. The load matching on the line can be accomplished by connecting |
| A. | a short circuit stub at the load |
| B. | an inductance at the load |
| C. | a short circuit stub at a specific distance from the load |
| D. | a capacitance at a specific distance from the load |
| Answer» C. a short circuit stub at a specific distance from the load | |
| 162. |
A plane wave is characterized by the wave is |
| A. | linearly polarized |
| B. | circularly polarized |
| C. | elliptically polarized |
| D. | unpolarized |
| Answer» D. unpolarized | |
| 163. |
A plane electromagnetic wave travels in dielectric medium of relative permittivity 9. Relative to free space, the velocity of propagation in the dielectric is |
| A. | increased by a factor of 9 |
| B. | increased by a factor of 3 |
| C. | unchanged |
| D. | reduced by a factor of 1/3 |
| Answer» E. | |
| 164. |
Consider a 300 &ohm;, quarter wave long at 1 GHz transmission line as shown in figure. It is connected to a 10 V, 50 &ohm; source at one end is left open circuited at the other end. The magnitude of the voltage at the open circuit end of the line is |
| A. | 10 V |
| B. | 5 V |
| C. | 60 V |
| D. | 60/7 volt |
| Answer» B. 5 V | |
| 165. |
A hollow rectangular waveguide has dimensions a = 2b. Calculate the amount of attenuation, if the frequency is 3 GHz, and b = 1 cm. |
| A. | 49 |
| B. | 47.33 |
| C. | 50.33 |
| D. | 50 |
| Answer» C. 50.33 | |
| 166. |
The phase angle corresponding to /4 in a standing-wave pattern is |
| A. | 30 |
| B. | 90 |
| C. | 135 |
| D. | 180 |
| Answer» C. 135 | |
| 167. |
Calculate the directivity of an antenna for E = 30 , H = 60 |
| A. | 46 |
| B. | 23 |
| C. | 50 |
| D. | 100 |
| Answer» C. 50 | |
| 168. |
Ferrite have |
| A. | low copper loss |
| B. | low eddy current loss |
| C. | low resistivity |
| D. | higher specific gravity compared to iron |
| Answer» D. higher specific gravity compared to iron | |
| 169. |
In a p type material the Fermi level is 0.3 eV above valence band. The concentration of acceptor atoms is increased. The new position of Fermi level is likely to be |
| A. | 0.5 eV above valence band |
| B. | 0.28 eV above valence band |
| C. | 0.1 eV above valence band |
| D. | below the valence band |
| Answer» C. 0.1 eV above valence band | |
| 170. |
In an n-p-n transistor, the majority carriers in the base are |
| A. | electrons |
| B. | holes |
| C. | both holes and electrons |
| D. | either holes or electrons |
| Answer» B. holes | |
| 171. |
The amount of photoelectric emission current depends on |
| A. | frequency of incident radiation |
| B. | intensity of incident radiation |
| C. | both frequency and intensity of incident radiation |
| D. | none of the above |
| Answer» C. both frequency and intensity of incident radiation | |
| 172. |
Assertion (A): A p-n junction has high resistance in reverse direction. Reason (R): When a reverse bias is applied to p-n junction, the width of depletion layer increases. |
| A. | Both A and R are true and R is correct explanation of A |
| B. | Both A and R are true but R is not a correct explanation of A |
| C. | A is true but R is false |
| D. | A is false but R is true |
| Answer» B. Both A and R are true but R is not a correct explanation of A | |
| 173. |
In the circuit of figure the function of resistor R and diode D are |
| A. | to limit the current and to protect LED against over voltage |
| B. | to limit the voltage and to protect LED against over current |
| C. | to limit the current and protect LED against reverse breakdown voltage. |
| D. | none of the above. |
| Answer» D. none of the above. | |
| 174. |
As compared to an ordinary semiconductor diode, a Schottky diode |
| A. | has higher reverse saturation current |
| B. | has higher reverse saturation current and higher cut in voltage |
| C. | has higher reverse saturation current and lower cut in voltage |
| D. | has lower reverse saturation current and lower cut in voltage |
| Answer» D. has lower reverse saturation current and lower cut in voltage | |
| 175. |
In a bipolar transistor which current is largest |
| A. | collector current |
| B. | base current |
| C. | emitter current |
| D. | base current or emitter current |
| Answer» D. base current or emitter current | |
| 176. |
The v-i characteristics of a FET is shown in figure. In which region is the device biased for small signal amplification |
| A. | AB |
| B. | BC |
| C. | CD |
| D. | BD |
| Answer» C. CD | |
| 177. |
Crossover distortion behaviour is characteristic of |
| A. | class A O/P stage |
| B. | class B O/P stage |
| C. | class AB output stage |
| D. | common pulse O/P state |
| Answer» C. class AB output stage | |
| 178. |
If aac for transistor is 0.98 then ac is equal to |
| A. | 51 |
| B. | 49 |
| C. | 47 |
| D. | 45 |
| Answer» C. 47 | |
| 179. |
Assertion (A): The conductivity of p type semiconductor is higher than that of intrinsic semiconductor. Reason (R): The addition of donor impurity creates additional energy levels below conduction band. |
| A. | Both A and R are true and R is correct explanation of A |
| B. | Both A and R are true but R is not a correct explanation of A |
| C. | A is true but R is false |
| D. | A is false but R is true |
| Answer» C. A is true but R is false | |
| 180. |
In an n-p-n transistor biased for operation in forward active region |
| A. | emitter is positive with respect to base |
| B. | collector is positive with respect to base |
| C. | base is positive with respect to emitter and collector is positive with respect to base |
| D. | none of the above |
| Answer» D. none of the above | |
| 181. |
An increase in temperature increases the width of depletion layer. |
| A. | True |
| B. | False |
| Answer» C. | |
| 182. |
In a 4 bit weighted resistor D/A converter, the resistor value corresponding to LSB is 32 k . The resistor value corresponding to MSB will be |
| A. | 32 K |
| B. | 16 K |
| C. | 8 K |
| D. | 4 K |
| Answer» E. | |
| 183. |
Consider a unity feedback control system with open-loop transfer function The steady state error of the system due to a unity step input is : |
| A. | zero |
| B. | K |
| C. | 1/K |
| D. | infinite |
| Answer» B. K | |
| 184. |
If x[n] then the sequence x[n] is |
| A. | non-periodic |
| B. | periodic |
| C. | depends on |
| D. | <i>n</i> |
| E. | none of these |
| Answer» B. periodic | |
| 185. |
The impulse response and the excitation function of a linear time invariant causal system are shown in figure (a) and (b) respectively. The output of the system at t = 2 sec is equal to |
| A. | 0 |
| B. | 2 |
| C. | <img src="/_files/images/electronics-and-communication-engineering/exam-question-papers/10-04-43-3.png"> |
| D. | <img src="/_files/images/electronics-and-communication-engineering/exam-question-papers/10-04-43-4.png"> |
| Answer» E. | |
| 186. |
Consider a stable and causal system with impulse response h(t) and system function H(S). Suppose H(S) is rational, contains a pole at S = - 2, and does not have a zero at the origin. The location of all other poles and zero is unknown for each of the following statements. Let us determine whether statement is true or false. f[h(t) e-3t] convergesh(t) has finite durationH(s) = H(- s) Choose correct option. |
| A. | 1 - True, 2 - False, 3 - True, 4 - False |
| B. | 1 - False, 2 - False, 3 - False, 4 - True |
| C. | 1 - False, 2 - False, 3 - False, 4 - False |
| D. | 1 - True, 2 - can't say, 3 - True, 4 - can't say |
| Answer» D. 1 - True, 2 - can't say, 3 - True, 4 - can't say | |
| 187. |
At room temperature the current in an intrinsic semiconductor is due to |
| A. | holes |
| B. | electrons |
| C. | ions |
| D. | holes and electrons |
| Answer» E. | |
| 188. |
Work function is the maximum energy required by the fastest electron at 0 K to escape from the metal surface. |
| A. | True |
| B. | False |
| Answer» C. | |
| 189. |
The most commonly used semiconductor material is |
| A. | silicon |
| B. | germanium |
| C. | mixture of silicon and germanium |
| D. | none of the above |
| Answer» B. germanium | |
| 190. |
In which of these is reverse recovery time nearly zero? |
| A. | Zener diode |
| B. | Tunnel diode |
| C. | Schottky diode |
| D. | PIN diode |
| Answer» D. PIN diode | |
| 191. |
A transistor has a current gain of 0.99 in the CB mode. Its current gain in the CC mode is |
| A. | 100 |
| B. | 99 |
| C. | 1.01 |
| D. | 0.99 |
| Answer» B. 99 | |
| 192. |
In the following non planar graph number of independent loop equations are |
| A. | 8 |
| B. | 12 |
| C. | 7 |
| D. | 5 |
| Answer» E. | |
| 193. |
A transmission line has a characteristic impedance of 50 and a resistance of 0.1 /m, if the line is distortion less, the attenuation constant (in Np/m) is |
| A. | 500 |
| B. | 5 |
| C. | 0.014 |
| D. | 0.002 |
| Answer» E. | |
| 194. |
A certain 8 bit uniform quantization PCM system can accommodate a signal ranging from - 1 V to + V. The rms value of the signal is V . The signal to quantization noise ratio is: |
| A. | 30 dB |
| B. | 46.91 dB |
| C. | 40 dB |
| D. | 49.92 dB |
| Answer» E. | |
| 195. |
In an ac circuit the fundamental component of current wave lags the corresponding voltage wave by 20 . The third harmonic component of current wave lags the corresponding voltage by an angle. |
| A. | less than 20 |
| B. | more than 20 |
| C. | equal to 20 |
| D. | equal to or more than 20 |
| Answer» C. equal to 20 | |
| 196. |
The output of a diode detector contains |
| A. | D.C. voltage |
| B. | modulating signal |
| C. | RF ripple |
| D. | all of the above |
| Answer» E. | |
| 197. |
Noise generated in a resistor is also known as |
| A. | partition noise |
| B. | white noise |
| C. | thermal noise |
| D. | shot noise |
| Answer» D. shot noise | |
| 198. |
Which of the following is used to provide tracking between RF amplifier and local oscillator stages of receiver? |
| A. | Variable tuning inductor |
| B. | Ganged tuning inductor |
| C. | Variable capacitor |
| D. | Variable preset |
| Answer» C. Variable capacitor | |
| 199. |
For global communication, the number of satellites needed is |
| A. | 1 |
| B. | 3 |
| C. | 10 |
| D. | 5 |
| Answer» C. 10 | |
| 200. |
In a radio receiver, if the intermediate frequency is too low |
| A. | Image-frequency rejection will improve |
| B. | Selectivity will be too sharp |
| C. | The frequency selectivity of the local oscillator will have to be lowered |
| D. | All of the above |
| Answer» C. The frequency selectivity of the local oscillator will have to be lowered | |