MCQOPTIONS
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MCQOPTIONS
This section includes 248 Mcqs, each offering curated multiple-choice questions to sharpen your Electromagnetic Theory knowledge and support exam preparation. Choose a topic below to get started.
| 151. |
160. Match the following: |
| A. | A - 1, B - 2, C - 3 |
| B. | A - 4, B - 1, C - 5 |
| C. | A - 3, B - 5, C - 4 |
| D. | A - 2, B - 4, C - 1 |
| Answer» E. | |
| 152. |
A transmission line of characteristic impedance 300 ohms is terminated by a load of (300 j 300) ohms. The transmission coefficient is |
| A. | 1.12 76.68 |
| B. | 1.08 76.68 |
| C. | 1.265 18.43 |
| D. | 0.719 18.45 |
| Answer» D. 0.719 18.45 | |
| 153. |
Which one of the following statements does not pertain to the equation . B = 0? |
| A. | There are no sinks and sources for magnetic fields |
| B. | Magnetic field is perpendicular to the electric field |
| C. | Single magnetic pole cannot exist |
| D. | B is solenoidal |
| Answer» C. Single magnetic pole cannot exist | |
| 154. |
The input impedance of a loss-less transmission line is 100 ohms when terminated in a short-circuit, and 64 ohms when terminated in an open circuit. The characteristic impedance of the line is |
| A. | 80 ohms |
| B. | 164 ohms |
| C. | 36 ohms |
| D. | 64 ohms |
| Answer» B. 164 ohms | |
| 155. |
Which of the following equation represents the Gauss law in a homogeneous isotropic medium? |
| A. | D. ds = dV |
| B. | H = D |
| C. | J + = 0 |
| D. | E = / |
| Answer» B. H = D | |
| 156. |
In order to radiate 100 W from a circular loop of circumference equal to 0.1 , the current required will be |
| A. | 10 A |
| B. | 100 A |
| C. | 200 A |
| D. | 400 A |
| Answer» B. 100 A | |
| 157. |
An antenna, when radiating, has a highly directional radiation pattern. When the antenna is receiving, its radiation pattern |
| A. | Is more directive |
| B. | Is less directive |
| C. | Is the same |
| D. | Exhibits no directivity at all |
| Answer» D. Exhibits no directivity at all | |
| 158. |
For a dipole antenna |
| A. | The radiation intensity is maximum along the normal to the dipole axis |
| B. | The current distribution along its length is uniform irrespective of the length |
| C. | The effective length equals to its physical length |
| D. | The input impedance is independent of the location of the feed-point |
| Answer» B. The current distribution along its length is uniform irrespective of the length | |
| 159. |
A plane electromagnetic wave travelling along +z-direction, has its electric field given by E |
| A. | Linearly polarised |
| B. | Right circularly polarised |
| C. | Left circularly polarised |
| D. | Elliptically polarised |
| Answer» D. Elliptically polarised | |
| 160. |
A very lossy, /4 long, 50 ohms transmission line is open circuited at the load end. The input impedance measured at the other end of the line is approximately |
| A. | 0 |
| B. | |
| C. | 50 ohms |
| D. | None of these |
| Answer» B. | |
| 161. |
The vector H in the far field of an antenna satisfies |
| A. | . H = 0 and H = 0 |
| B. | . H 0 and H 0 |
| C. | . H = 0 and H 0 |
| D. | . H 0 and H = 0 |
| Answer» D. . H 0 and H = 0 | |
| 162. |
Consider the following statements: For electromagnetic waves propagating in free space: |
| A. | 1 and 3 |
| B. | 1 and 4 |
| C. | 2 and 3 |
| D. | 2 and 4 |
| Answer» B. 1 and 4 | |
| 163. |
The input impedance of a short circuited quarter wave long transmission line is |
| A. | Purely reactive |
| B. | Purely resistive |
| C. | Dependent on the characteristic impedance of the line |
| D. | None of the above |
| Answer» E. | |
| 164. |
The input impedance of a 8 long short-circuited section of a lossless transmission line is |
| A. | Zero |
| B. | Inductive |
| C. | Capacitive |
| D. | Infinite |
| Answer» C. Capacitive | |
| 165. |
The polarization of wave with electric field vector E = E |
| A. | Linear |
| B. | Elliptical |
| C. | Left hand circular |
| D. | Right hand circular |
| Answer» B. Elliptical | |
| 166. |
A positive charge of Q coulomb is located at point A (0, 0, 3) and a negative charge of magnitude Q coulomb is located at point B (0, 0, 3). The electric field intensity at point C (4, 0, 0) is in the |
| A. | Negative x-direction |
| B. | Negative z-direction |
| C. | Positive x-direction |
| D. | Positive z-direction |
| Answer» C. Positive x-direction | |
| 167. |
Polystyrene has a relative permittivity of 2.7. If the wave is incident at an angle ' ' of 30 from air on-to polystyrene, the angle of transmission will be nearly |
| A. | 0.2 |
| B. | 2 |
| C. | 18 |
| D. | 48 |
| Answer» D. 48 | |
| 168. |
The equation . j = 0 is known as |
| A. | Poisson's equation |
| B. | Laplace equation |
| C. | Continuity equation |
| D. | Maxwell equation |
| Answer» C. Continuity equation | |
| 169. |
A 3 F capacitor is charged by a constant current of 2 A for 6 seconds. The voltage across the capacitor at the end of charging will be |
| A. | 3 V |
| B. | 4 V |
| C. | 6 V |
| D. | 9 V |
| Answer» C. 6 V | |
| 170. |
For incidence from dielectric medium ( |
| A. | 30 and 30 |
| B. | 30 and 60 |
| C. | 60 and 30 |
| D. | 60 and 60 |
| Answer» D. 60 and 60 | |
| 171. |
The equation for distortionless transmission if R/ G = L/ C. To attain it, in a line |
| A. | Of all the parameters, it is best to increase L for distortionless transmission |
| B. | Keeping R and L constant it is preferrable to increase or decrease G and C |
| C. | The inductance can be added at any interval |
| D. | The inductance can be of any value |
| Answer» B. Keeping R and L constant it is preferrable to increase or decrease G and C | |
| 172. |
The directivity of an isotropic antenna is |
| A. | Zero |
| B. | Less than unity |
| C. | Unity |
| D. | Infinity |
| Answer» D. Infinity | |
| 173. |
A transmission line of characteristic impedance Z |
| A. | (30 + j 40) ohms |
| B. | (30 j 40) ohms |
| C. | (50 + j 40) ohms |
| D. | (50 j 40) ohms |
| Answer» C. (50 + j 40) ohms | |
| 174. |
Which of the following pairs of parameters and expressions is/are correctly matched? |
| A. | 1 alone |
| B. | 2 and 3 |
| C. | 1 and 3 |
| D. | 1 and 2 |
| Answer» B. 2 and 3 | |
| 175. |
When a lossy capacitor with a dielectric of permittivity and conductivity operates at a frequency , the loss tangent for the capacitor is given by |
| A. | / |
| B. | / |
| C. | / |
| D. | |
| Answer» D. | |
| 176. |
The critical frequency of an ionosphere layer is 10 MHz. What is the maximum launching angle from the horizon for which a 20 MHz wave will be reflected by the layer |
| A. | 0 |
| B. | 30 |
| C. | 60 |
| D. | 90 |
| Answer» C. 60 | |
| 177. |
Two electric dipoles aligned parallel to each other and having the same axis exert a force F on each other, when a distance d apart. If the dipoles are a distance 2d apart, then the mutual force between them would be |
| A. | F/ 2 |
| B. | F/ 4 |
| C. | F/ 8 |
| D. | F/ 16 |
| Answer» E. | |
| 178. |
If a conductor of cross-section A and carrying a current current | |
| A. | <table><tr><td></td><td></td><td> </td></tr><br><tr><td rowspan="2">&plus;</td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>B<sub>0</sub></center></td><td>a<sub>z</sub> N/m<sup>2</sup></td></tr><tr><td style="text-align: center;">a</td></tr></table> |
| B. | <table><tr><td></td><td></td><td> </td></tr><br><tr><td rowspan="2">&plus;</td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>B<sub>0</sub></center></td><td>a<sub>x</sub> N/m<sup>2</sup></td></tr><tr><td style="text-align: center;">a</td></tr></table> |
| C. | <table><tr><td></td><td></td><td> </td></tr><br><tr><td rowspan="2"> </td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>B<sub>0</sub></center></td><td>a<sub>z</sub> N/m<sup>3</sup></td></tr><tr><td style="text-align: center;">a</td></tr></table> |
| D. | <table><tr><td></td><td></td><td> </td></tr><br><tr><td rowspan="2">&plus;</td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>B<sub>0</sub></center></td><td>a<sub>y</sub> N/m<sup>3</sup></td></tr><tr><td style="text-align: center;">a</td></tr></table> |
| Answer» D. <table><tr><td></td><td></td><td> </td></tr><br><tr><td rowspan="2">&plus;</td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>B<sub>0</sub></center></td><td>a<sub>y</sub> N/m<sup>3</sup></td></tr><tr><td style="text-align: center;">a</td></tr></table> | |
| 179. |
Consider the following statements associated with the basic electrostatic properties of ideal conductors: |
| A. | 1, 2, 3 and 4 are correct |
| B. | 3, 4 and 5 are correct |
| C. | 1, 2 and 3 are correct |
| D. | 2 and 3 are correct |
| Answer» B. 3, 4 and 5 are correct | |
| 180. |
Three concentric spherical shells of radii R |
| A. | 0 and 4 |
| B. | 3 and 1 |
| C. | 3 and 7 |
| D. | 2 and 6 |
| Answer» C. 3 and 7 | |
| 181. |
Three concentric conducting spherical surfaces of radii R |
| A. | 0, 4 |
| B. | 3, 1 |
| C. | 3, 7 |
| D. | 2, 6 |
| Answer» C. 3, 7 | |
| 182. |
Transmission of power to a load over a transmission line achieves optimum value when standing-wave ratio (SWR) becomes |
| A. | 2: 1 |
| B. | 1: 2 |
| C. | 1: 1 |
| D. | 1: |
| E. | <span style=" text-decoration: overline;">2</span> |
| Answer» D. 1: | |
| 183. |
When electromagnetic waves are reflected at an angle from a wall, their wavelength along the wall is |
| A. | The same as in free space |
| B. | The same as the wavelength perpendicular to the wall |
| C. | Shortened because of the Doppler effect |
| D. | Greater than in the actual direction of propagation |
| Answer» E. | |
| 184. |
When an iron core is placed between the poles of a permanent magnet as shown in figure below, the magnetic field pattern is |
| A. | <img src="http://images.interviewmania.com/wp-content/uploads/2019/05/Capture-84-1.png"> |
| B. | <img src="http://images.interviewmania.com/wp-content/uploads/2019/05/Capture-84-2.png"> |
| C. | <img src="http://images.interviewmania.com/wp-content/uploads/2019/05/Capture-84-3.png"> |
| D. | <img src="http://images.interviewmania.com/wp-content/uploads/2019/05/Capture-84-4.png"> |
| Answer» D. <img src="http://images.interviewmania.com/wp-content/uploads/2019/05/Capture-84-4.png"> | |
| 185. |
Consider the following statements regarding Maxwell's equations in differential form (symbols have their usual meaning) |
| A. | 1 and 2 are correct |
| B. | 2 and 3 are correct |
| C. | 3 and 4 are correct |
| D. | 1 and 4 are correct |
| Answer» D. 1 and 4 are correct | |
| 186. |
A plane wave propagating through a medium [E |
| A. | 377 |
| B. | 198.5 180 |
| C. | 182.9 14 |
| D. | 133.3 |
| Answer» B. 198.5 180 | |
| 187. |
In air a lossless transmission line of length 50 cm with L = 10 H/m, C = 40 pF/m is operated at 25 MHz. Its electrical path length is |
| A. | 0.5 metre |
| B. | metre |
| C. | /2 radians |
| D. | 280 degrees |
| Answer» D. 280 degrees | |
| 188. |
If wave of critical frequency 30 MHz is departing an angle of 60 then the MUF is given to be |
| A. | 10 MHz |
| B. | 15 MHz |
| C. | 30 MHz |
| D. | 60 MHz |
| Answer» E. | |
| 189. |
An open wire transmission line has R = 5 /m, L = 5.2 10 |
| A. | 179.44 + j 26.50, 181.39 8.40 |
| B. | 15.623 + j 0.0205, 15.623 0.075 |
| C. | 200 + j 26.50, 181.39 8.40 |
| D. | 220 + j 26.50, 244 0.75 |
| Answer» C. 200 + j 26.50, 181.39 8.40 | |
| 190. |
A transmitting antenna radiates 251 W isotropically. A receiving antenna located 100 m away from the transmitting antenna has an effective aperture of 500 cm |
| A. | 10 W |
| B. | 1 W |
| C. | 20 W |
| D. | 100 W |
| Answer» E. | |
| 191. |
In a twin wire transmission line in air the adjacent voltage maxima are at 12.5 cm and 27.5 cm. The operating frequency is |
| A. | 300 MHz |
| B. | 1 GHz |
| C. | 2 GHz |
| D. | 6.28 GHz |
| Answer» D. 6.28 GHz | |
| 192. |
For field of an antenna varies with distance r as |
| A. | <table><tr><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>1</center></td></tr><tr><td style="text-align: center;">r</td></tr></table> |
| B. | <table><tr><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>1</center></td></tr><tr><td style="text-align: center;">r<sup>2</sup></td></tr></table> |
| C. | <table><tr><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>1</center></td></tr><tr><td style="text-align: center;">r<sup>3</sup></td></tr></table> |
| D. | <table><tr><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>1</center></td></tr><tr><td style="text-align: center;"> <span style=" text-decoration: overline;">r</span></td></tr></table> |
| Answer» B. <table><tr><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>1</center></td></tr><tr><td style="text-align: center;">r<sup>2</sup></td></tr></table> | |
| 193. |
A loop is rotating about the y-axis in a magnetic field |
| A. | Zero |
| B. | Due to rotation only |
| C. | Due to transformer action only |
| D. | Due to both rotation and transformer action |
| Answer» E. | |
| 194. |
The radiation resistance of a circular loop of a turn is 0.01 . The radiation resistance of five turns of such a loop will be |
| A. | 0.002 |
| B. | 0.01 |
| C. | 0.05 |
| D. | 0.25 |
| Answer» D. 0.25 | |
| 195. |
Rectangular waveguide is designed to propagate the dominant mode TE |
| A. | 3.75 cm, 1.875 cm |
| B. | 4 cm, 2 cm |
| C. | 8 cm, 4 cm |
| D. | 2.54 cm, 1.27 cm |
| Answer» B. 4 cm, 2 cm | |
| 196. |
A line with lumped parameters of 10 T sections series resistances of 10 ohms per section and 200 ohms shunt resistance is matched to a generator with emf of 3 volts and terminated by its characteristic impedance. The characteristic impedance is given by |
| A. | 45 |
| B. | 22.4 |
| C. | 90 |
| D. | 180 |
| Answer» B. 22.4 | |
| 197. |
The main difference between operation of a transmission lines and waveguide is that |
| A. | The latter are not distributed like transmission line |
| B. | The former can use stubs and quarter wave transformers unlike the latter |
| C. | Transmission lines use the principal mode of propagation and, therefore, don't suffer from low frequency cut-off |
| D. | Terms such as impedance matching and standing wave ratio can't be applied to waveguide |
| Answer» D. Terms such as impedance matching and standing wave ratio can't be applied to waveguide | |
| 198. |
A transmitter radiates power of 20 kW and its base current is 18 A. The radiation resistance of the antenna is |
| A. | 1111 |
| B. | 900 |
| C. | 75 |
| D. | 62 |
| Answer» E. | |
| 199. |
The wavelength of a wave with propagation constant (0.1 + j 0.2 ) m |
| A. | <table><tr><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>2</center></td><td rowspan="2">m</td></tr><tr><td style="text-align: center;"> <span style=" text-decoration: overline;">0.05</span><br></td></tr></table> |
| B. | 10 m |
| C. | 20 m |
| D. | 30 m |
| Answer» C. 20 m | |
| 200. |
The time average Poynting vector in W/m |
| A. | <table><tr><td rowspan="2">-<br></td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>2.4</center></td><td> </td><td rowspan="2"><br>a<sub>z</sub></td></tr> <tr><td style="text-align: center;"> </td></tr> </table> |
| B. | <table><tr><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>2.4</center></td><td> </td><td rowspan="2"><br>a<sub>z</sub></td></tr><br><tr><td style="text-align: center;"> </td></tr><br></table> |
| C. | <table><tr><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>4.8</center></td><td> </td><td rowspan="2"><br>a<sub>z</sub></td></tr><br><tr><td style="text-align: center;"> </td></tr><br></table> |
| D. | <table><tr><td rowspan="2"> - </td><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>4.8</center></td><td> </td><td rowspan="2"><br>a<sub>z</sub></td></tr><br><tr><td style="text-align: center;"> </td></tr><br></table> |
| Answer» B. <table><tr><td style="border-bottom:1px solid #000000;vertical-align:bottom;padding-bottom:2px;"><center>2.4</center></td><td> </td><td rowspan="2"><br>a<sub>z</sub></td></tr><br><tr><td style="text-align: center;"> </td></tr><br></table> | |