McqMate
| 101. |
Maxwell's equations in __________ form give unformation at points of discontinuity in electromagnetic fields. |
| A. | Differential |
| B. | Integral |
| C. | Algebraic |
| D. | None of these |
| Answer» B. Integral | |
| 102. |
Another boundary condition using Maxwell's equations is given as __________. |
| A. | Htan '1' + Htan '2' = 0 |
| B. | Htan '1' − Htan '2' = 0 |
| C. | Htan '1' + Htan '2' = Js |
| D. | Htan '1'− Htan '2' = Js |
| Answer» D. Htan '1'− Htan '2' = Js | |
| 103. |
At the point of discontinuity, __________ component of magnetic flux density is continuous. |
| A. | Tangential |
| B. | Normal |
| C. | None of these |
| D. | Cannot say |
| Answer» B. Normal | |
| 104. |
For those surfaces where surface charge density is __________ normal component of electric flux density is continuous. |
| A. | Infinity |
| B. | Unity |
| C. | Zero |
| D. | None of these |
| Answer» C. Zero | |
| 105. |
Waves are used in __________. |
| A. | TV |
| B. | Radio |
| C. | Radar |
| D. | All of these |
| Answer» D. All of these | |
| 106. |
Displacement current density ____________ current passing through a capacitor. |
| A. | Represents |
| B. | Does not represent |
| C. | Is the same as |
| D. | None of these |
| Answer» B. Does not represent | |
| 107. |
Line integral of an electric field around a closed path is __________. |
| A. | infinity |
| B. | unity |
| C. | zero |
| D. | None of these |
| Answer» C. zero | |
| 108. |
__________ are caused by accelerated charges |
| A. | Time-varying fields |
| B. | Waves |
| C. | Both (a) and (b) |
| D. | None of these |
| Answer» C. Both (a) and (b) | |
| 109. |
At the Brewster angle, polarization ______________. |
| A. | Cannot be reflected |
| B. | Is reflected at 30° |
| C. | Is reflected at 90° |
| D. | None of these |
| Answer» A. Cannot be reflected | |
| 110. |
Wave number has units of____________. |
| A. | Radians |
| B. | Meter |
| C. | Radians/meter |
| D. | None of these |
| Answer» C. Radians/meter | |
| 111. |
Wave speed in terms of frequency f and wavelength λ is expressed as _________. |
| A. | f/λ |
| B. | λ/f |
| C. | λ f |
| D. | (λ + f) |
| Answer» C. λ f | |
| 112. |
For a lossy dielectric medium, ____________. |
| A. | σ = 0 |
| B. | σ ≠ 0 |
| C. | None of these |
| D. | Cannot say |
| Answer» B. σ ≠ 0 | |
| 113. |
Wave attenuation is given as ______________. |
| A. | e+βx |
| B. | e-βx |
| C. | e+αx |
| D. | e−αx |
| Answer» D. e−αx | |
| 114. |
In the case of a perfect dielectric medium, phase constant ______________ as conductivity increases. |
| A. | Increases |
| B. | Decreases |
| C. | Remains unchanged |
| D. | None of these |
| Answer» A. Increases | |
| 115. |
Phase velocity is given as _________. |
| A. | ωβ |
| B. | βω |
| C. | β/ω |
| D. | None of these |
| Answer» C. β/ω | |
| 116. |
In good conductors, rate of attenuation is __________. |
| A. | Small |
| B. | Large |
| C. | Infinity |
| D. | Zero |
| Answer» C. Infinity | |
| 117. |
Power density has _________________. |
| A. | A DC component |
| B. | A second harmonic component |
| C. | Both (a) and (b) |
| D. | None of these |
| Answer» C. Both (a) and (b) | |
| 118. |
Reflection coefficient Γ is __________. |
| A. | ≥100 |
| B. | = 10 |
| C. | ≤ 1 |
| D. | None of these |
| Answer» C. ≤ 1 | |
| 119. |
Which of the following expressions is correct? |
| A. | (1 + Γ) = τ |
| B. | (1 + τ) = Γ |
| C. | (1 + Γ) τ = 0 |
| D. | (1 + τ)Γ = 0 |
| Answer» A. (1 + Γ) = τ | |
| 120. |
Standing wave consists of two travelling waves of ____________ amplitudes and _____________ is direction. |
| A. | Unequal, same |
| B. | Unequal, opposite |
| C. | Equal, same |
| D. | Equal, opposite |
| Answer» D. Equal, opposite | |
| 121. |
SNR ranges from ______. |
| A. | 0 to 1 |
| B. | 1 to 10 |
| C. | 10 to 100 |
| D. | 1 to ∞ |
| Answer» D. 1 to ∞ | |
| 122. |
The Smith chart is a ________ dimensional representation of complex impedances with respect to coordinates. |
| A. | Two |
| B. | Three |
| C. | Four |
| D. | None of these |
| Answer» C. Four | |
| 123. |
In a _________ transmission line, the reflection coefficient domain is a circle of unitary radius. |
| A. | Lossy |
| B. | Lossless |
| C. | None of these |
| D. | Cannot say |
| Answer» B. Lossless | |
| 124. |
The Smith chart represents a family of circles obtained by varying normalized resistance in the range of __________. |
| A. | −1 to 0 |
| B. | 0 to 1 |
| C. | 0 to ∞ |
| D. | −∞ to ∞ |
| Answer» C. 0 to ∞ | |
| 125. |
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» D. −∞ to ∞ | |
| 126. |
Smith charts depict a wide impedance range of transmitter for _______VSWR. |
| A. | Low |
| B. | High |
| C. | Medium |
| D. | None of these |
| Answer» B. High | |
| 127. |
A cable or a wire is considered as a transmission line if its length is _________of the wavelength of the signal travelling through it. |
| A. | Greater than 1/10 |
| B. | Less than 1/10 |
| C. | Greater than 1/5 |
| D. | Less than 1/5 |
| Answer» A. Greater than 1/10 | |
| 128. |
Transmission lines facilitate _________propagation of energy. |
| A. | Guided |
| B. | Unguided |
| C. | None of these |
| D. | Cannot say |
| Answer» A. Guided | |
| 129. |
A transmission line is specified in terms of _________. |
| A. | R, G,L |
| B. | G, L,C |
| C. | R, G, L,C |
| D. | None of these |
| Answer» C. R, G, L,C | |
| 130. |
In planar transmission lines, C = _________. |
| A. | σ b/d |
| B. | μ d/b |
| C. | b/d |
| D. | None of these. |
| Answer» C. b/d | |
| 131. |
In a microstrip line, there is _________metal strip over the substrate. |
| A. | A thin |
| B. | A thick |
| C. | No |
| D. | None of these |
| Answer» A. A thin | |
| 132. |
In a fully lossless line, σ = _________. |
| A. | 0 |
| B. | 1 |
| C. | ∞ |
| D. | None of these. |
| Answer» C. ∞ | |
| 133. |
In a distortionless line, attenuation constant α is frequency _________. |
| A. | Dependent |
| B. | Independent |
| C. | None of these |
| D. | Cannot say |
| Answer» B. Independent | |
| 134. |
A distortion less line has _________. |
| A. | Non-vanishing attenuation constant |
| B. | Constant velocity |
| C. | Constant real characteristic impedance |
| D. | All of these |
| Answer» D. All of these | |
| 135. |
Voltage reflection coefficient is the ratio of _________ wave to _______ wave. |
| A. | Incident, reflected |
| B. | Reflected, incident |
| C. | Incident, absorbed |
| D. | Absorbed, incident |
| Answer» B. Reflected, incident | |
| 136. |
________ are very efficient in a frequency range of 3-300 GHz. |
| A. | Transmission line |
| B. | Wave guides |
| C. | Both (a) and (b) |
| D. | None of these |
| Answer» B. Wave guides | |
| 137. |
Wave guides ________ in DC applications. |
| A. | Can also be used |
| B. | Cannot be used |
| C. | None of these |
| D. | Cannot say |
| Answer» B. Cannot be used | |
| 138. |
Wave guides are a type of _________ filter. |
| A. | Low pass |
| B. | All pass |
| C. | Band pass |
| D. | High pass |
| Answer» D. High pass | |
| 139. |
For lossless wave guides, σc ________and σ ______ |
| A. | ∞, 0 |
| B. | 0, ∞ |
| C. | 0, 0 |
| D. | ∞, ∞ |
| Answer» A. ∞, 0 | |
| 140. |
In the TM mode, Ez _____ and Hz = ________. |
| A. | 0, 0 |
| B. | 0, ∞ |
| C. | ∞ 0 |
| D. | None of these |
| Answer» D. None of these | |
| 141. |
In the TEM mode, Ez ______ and Hz =_______ |
| A. | 0, 0 |
| B. | 0, ∞ |
| C. | ∞, 0 |
| D. | None of these |
| Answer» A. 0, 0 | |
| 142. |
Below the cut-off frequency, there is_______________. |
| A. | Attenuation |
| B. | No attenuation |
| C. | Amplification |
| D. | None of these. |
| Answer» A. Attenuation | |
| 143. |
Cut-off wavelength λc in the TE10 mode is ____________. |
| A. | a |
| B. | 2a |
| C. | 4a |
| D. | 8a |
| Answer» B. 2a | |
| 144. |
_______ velocity is the one at which loss of constant phase propagates down the guide. |
| A. | Medium |
| B. | Phase |
| C. | Group |
| D. | None of these |
| Answer» B. Phase | |
| 145. |
Information or energy through the wave guide travels at _______ velocity. |
| A. | Medium |
| B. | Phase |
| C. | Group |
| D. | None of these |
| Answer» C. Group | |
| 146. |
_______velocity is that whose resultant repeated reflected waves travel down the guide. |
| A. | Medium |
| B. | Phase |
| C. | Group |
| D. | None of these |
| Answer» C. Group | |
| 147. |
________ vector is needed to determine power flow in wave guides. |
| A. | Poynting |
| B. | Average Poynting |
| C. | Power |
| D. | Phase |
| Answer» B. Average Poynting | |
| 148. |
Surface current density K on wave guide walls for ______ is given as |
| A. | TM mode |
| B. | TE mode |
| C. | Both (a) and (b) |
| D. | None of these |
| Answer» C. Both (a) and (b) | |
| 149. |
At _______ frequencies, RLC resonant circuits are replaced by electromagnetic cavity resonators. |
| A. | Low |
| B. | Medium |
| C. | High |
| D. | None of these |
| Answer» C. High | |
| 150. |
Resonator cavities are used in _______. |
| A. | Klystron tubes |
| B. | Band-pass filters |
| C. | Wave meters |
| D. | All of these |
| Answer» D. All of these | |
| 151. |
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» B. Shorted at both ends | |
| 152. |
Antenna tuning is done by changing its___________. |
| A. | Inductive reactances |
| B. | Capacitive reactances |
| C. | Both (a) and (b) |
| D. | None of these |
| Answer» C. Both (a) and (b) | |
| 153. |
Resonant frequency of an antenna depends upon its___________. |
| A. | Physical length |
| B. | Electrical length |
| C. | None of these |
| D. | Cannot say |
| Answer» B. Electrical length | |
| 154. |
Impedance of an antenna is matched to feed___________. |
| A. | Line |
| B. | Radio |
| C. | Both (a) and (b) |
| D. | None of these |
| Answer» C. Both (a) and (b) | |
| 155. |
In low-power applications, ideal SWR is___________. |
| A. | 1:1 |
| B. | 1:2 |
| C. | 2:1 |
| D. | 2:2 |
| Answer» A. 1:1 | |
| 156. |
Which of the following is a low-gain antenna? |
| A. | Dish antenna on a space craft |
| B. | Wi-Fi antenna |
| C. | Both (a) and (b) |
| D. | None of these |
| Answer» B. Wi-Fi antenna | |
| 157. |
In the case of an ideal isotropic antenna, the geometric radiation pattern is___________. |
| A. | Circle |
| B. | Sphere |
| C. | Parabola |
| D. | Hyperbola |
| Answer» B. Sphere | |
| 158. |
Antenna gain is minimum at radiation pattern___________. |
| A. | Side lobes |
| B. | Back lobes |
| C. | None of these |
| D. | Gain is independent of the radiation pattern |
| Answer» A. Side lobes | |
| 159. |
Elliptical polarization can be of___________. |
| A. | Left hand |
| B. | Right hand |
| C. | Either (a) or (b) |
| D. | None of these |
| Answer» C. Either (a) or (b) | |
| 160. |
Transmitters used on vehicles are__________ polarized. |
| A. | Linearly |
| B. | Circularly |
| C. | Both (a) and (b) |
| D. | None of these |
| Answer» B. Circularly | |
| 161. |
Antenna bandwidth can be increased by using__________. |
| A. | A feed horn |
| B. | Thicker wires |
| C. | Cages |
| D. | All of these |
| Answer» D. All of these | |
| 162. |
Antenna array is__________. |
| A. | 1-D |
| B. | 2-D |
| C. | Either (a) or (b) |
| D. | None of these |
| Answer» C. Either (a) or (b) | |
| 163. |
Array factor depends upon__________. |
| A. | Number of elements |
| B. | Spacing among elements |
| C. | Phase of the applied signal |
| D. | All of these |
| Answer» D. All of these | |
| 164. |
If antenna directivity and antenna gain are equal, then antenna efficiency is __________%. |
| A. | 20 |
| B. | 50 |
| C. | 75 |
| D. | 100 |
| Answer» D. 100 | |
| 165. |
If antenna array elemental spacing is large, then directivity will be__________. |
| A. | Small |
| B. | More |
| C. | None of these |
| D. | Cannot say |
| Answer» B. More | |
| 166. |
On the basis of the radiation pattern, an antenna array is__________. |
| A. | Broadside |
| B. | End fire |
| C. | Either (a) or (b) |
| D. | None of these |
| Answer» C. Either (a) or (b) | |
| 167. |
In__________array, radiation is perpendicular to array orientation. |
| A. | Broadside |
| B. | End fire |
| C. | None of these |
| D. | Cannot say |
| Answer» A. Broadside | |
| 168. |
In__________array, radiation is in the same direction as the array orientation. |
| A. | Broadside |
| B. | End fire |
| C. | None of these |
| D. | Cannot say |
| Answer» D. Cannot say | |
| 169. |
A large aperture means antenna gain will be__________. |
| A. | Large |
| B. | Small |
| C. | None of these |
| D. | Cannot say |
| Answer» B. Small | |
| 170. |
A short dipole antenna is__________. |
| A. | Left end-fed |
| B. | Right end-fed |
| C. | Centre-fed |
| D. | None of these |
| Answer» C. Centre-fed | |
| 171. |
The force between two charges is 120 N. if the distance between the charge is doubled, the force will be |
| A. | 60 N |
| B. | 30 N |
| C. | 40 N |
| D. | 15 N |
| Answer» B. 30 N | |
| 172. |
The electric field intensity at a point situated at 4 meters away from a point charge 200 N/C. if the distance is reduced to 2 meters, the field intensity will be. |
| A. | 400 N/C |
| B. | 600 N/C |
| C. | 800 N/C |
| D. | 1200 N/C |
| Answer» C. 800 N/C | |
| 173. |
A hole of radius b (b < a) is now drilled along the length of the wire at a distance d from the center of the wire as shown below. The magnetic field inside the hole is |
| A. | uniform and depends only on d |
| B. | uniform and depends only on b |
| C. | uniform and depends on both b and d |
| D. | non uniform |
| Answer» C. uniform and depends on both b and d | |
| 174. |
The line of force due to charged particles are always |
| A. | Always straight |
| B. | Always curve |
| C. | Always circle |
| D. | None of the above |
| Answer» B. Always curve | |
| 175. |
The electric field at a point situated as a distance d from straight charged conductor is |
| A. | Proportional to d |
| B. | Inversely proportional to d |
| C. | Inversely proportional to distance |
| D. | None of the above |
| Answer» B. Inversely proportional to d | |
| 176. |
The direction of electric field due to +0 positive charge is |
| A. | Away from the charge |
| B. | Towards the charge |
| C. | Both (a) & (b) |
| D. | None of the above |
| Answer» A. Away from the charge | |
| 177. |
A field line and equipotential surface are |
| A. | Always parallel |
| B. | Always at 90 angle |
| C. | Inclined at any angle |
| D. | None of the above |
| Answer» A. Always parallel | |
| 178. |
The ability of charged bodies to exert force on any another is attributed to the existence of |
| A. | Electrons |
| B. | Protons |
| C. | Neutrons |
| D. | Electric field |
| Answer» C. Neutrons | |
| 179. |
A capacitor stored 0.24 coulombs at 10 volts ,its capacitance is |
| A. | 0.024F |
| B. | 0.12 F |
| C. | 0.6 F |
| D. | 0.8 F |
| Answer» A. 0.024F | |
| 180. |
For making a capacitor , it is better to select a dielectric having |
| A. | Low permittivity |
| B. | High permittivity |
| C. | Permittivity same as that of air |
| D. | Permittivity slightly more than that of air |
| Answer» B. High permittivity | |
| 181. |
The units of capacitance are |
| A. | Volts/coulomb |
| B. | Coulombs/volt |
| C. | Ohms |
| D. | Henry/wb |
| Answer» B. Coulombs/volt | |
| 182. |
If three 15 uf capacitors are connected in series , the net capacitance is |
| A. | 5uf |
| B. | 30 Ue |
| C. | 40 uF |
| D. | 50 UF |
| Answer» A. 5uf | |
| 183. |
A dielectric material must be |
| A. | Resistor |
| B. | Insulator |
| C. | Good conductor |
| D. | Semi conductor |
| Answer» B. Insulator | |
| 184. |
An electrolytic capacitor can be used for |
| A. | D.C. only |
| B. | AC .only |
| C. | Both |
| D. | C. as well as A.C. |
| Answer» A. D.C. only | |
| 185. |
The capacitance of a capacitor is not affected by |
| A. | Distance between plates |
| B. | Area of plates |
| C. | Thickness of plates |
| D. | All of the above |
| Answer» C. Thickness of plates | |
| 186. |
Which of the following is not a vector? |
| A. | Linear momentum |
| B. | Angular momentum |
| C. | Electric field |
| D. | Electric potential |
| Answer» A. Linear momentum | |
| 187. |
Two plates of parallel plate capacitor after being charged from a constant voltage source are separated apart by means of insulated handles, then the |
| A. | Voltage across the plates inceases |
| B. | Voltage across the plates decreases |
| C. | Charge on the capacitor decreases |
| D. | Charge on the capacitor increases |
| Answer» B. Voltage across the plates decreases | |
| 188. |
If A.C. voltage is applied to capacititve circuit , th alternating current can flow in the circuit because |
| A. | Varying voltage produces the charging and discharging currents |
| B. | Of high peak value |
| C. | Discharge current can flow |
| D. | Charging current can flow |
| Answer» A. Varying voltage produces the charging and discharging currents | |
| 189. |
Voltage applied across a ceramic dielectric produces an electrolytic field 100 times greater than air. What will be the value of dielectric constant? |
| A. | 50 |
| B. | 100 |
| C. | 150 |
| D. | 200 |
| Answer» B. 100 | |
| 190. |
Which of the following statements is correct? |
| A. | Air capacitors have a blackband to indicate the outside foil |
| B. | Electrolytic capacitor must be connected in the correct polarity |
| C. | Ceramic capacitors must be connected in the correct polarity |
| D. | Mica capacitors are available in capacitance value of 1 to 10 pf |
| Answer» B. Electrolytic capacitor must be connected in the correct polarity | |
| 191. |
The dissipation factor of good dielectric is of the order of |
| A. | 0.0002 |
| B. | 0.002 |
| C. | 0.02 |
| D. | 0.2 |
| Answer» A. 0.0002 | |
| 192. |
“ the total electric flux through any closed surface surrounding charges is equal to the amount of charge enclosed “. |
| A. | Coulomb’s square law |
| B. | Gauss’s law |
| C. | Maxwell’s first law |
| D. | Maxwell’s second law |
| Answer» B. Gauss’s law | |
| 193. |
Which of the following statement is true? |
| A. | The current in the discharging capacitor grows linearly |
| B. | The current in the discharging capacitor grows exponentially |
| C. | The current in the discharging capacitor decays exponentially |
| D. | The current in the discharging capacitor decreases constantally |
| Answer» B. The current in the discharging capacitor grows exponentially | |
| 194. |
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» A. E = D/E | |
| 195. |
In a capacitor the electric charge is stored in |
| A. | Glass |
| B. | Vacuum |
| C. | Ceramics |
| D. | Oils |
| Answer» C. Ceramics | |
| 196. |
Which of the following capacitors will have the least variation? |
| A. | Paper capacitor |
| B. | Ceramic capacitor |
| C. | Silver plated mica capacitor |
| D. | None of the above |
| Answer» C. Silver plated mica capacitor | |
| 197. |
Which of the following capacitor has relatively shorter shelf life? |
| A. | Mica capacitor |
| B. | Electrolytic capacitor |
| C. | Ceramic capacitor |
| D. | Paper capacitor |
| Answer» B. Electrolytic capacitor | |
| 198. |
The sparking between two electrical contacts can be reduced by inserting a |
| A. | Capacitor in parallel with contacts |
| B. | Capacitor in series with each contact |
| C. | Resistance in line |
| D. | None of the above |
| Answer» A. Capacitor in parallel with contacts | |
| 199. |
In the case of lossy capacitor, its series equivalent resistance value will be |
| A. | Small |
| B. | Very small |
| C. | Large |
| D. | Zero |
| Answer» B. Very small | |
| 200. |
The power dissipated in a pure capacitor is |
| A. | Zero |
| B. | Proportional to applied voltage |
| C. | Proportional to value of capacitance |
| D. | Both (b) and (c) above |
| Answer» A. Zero | |
Done Reading?