MCQOPTIONS
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MCQOPTIONS
This section includes 58 Mcqs, each offering curated multiple-choice questions to sharpen your Electromagnetic Theory knowledge and support exam preparation. Choose a topic below to get started.
| 51. |
A 1 km long microwave link uses two antennas each having 30 dB gain. If the power transmitted by one antenna is 1 watt 3 GHz, the power received by the other antenna is approximately |
| A. | 98.6 μW |
| B. | 76.8 μW |
| C. | 63.4 μW |
| D. | 55.2 μW |
| Answer» C. 63.4 μW | |
| 52. |
Direction: Given question consists of two statements, one labeled as the 'Assertion (A)' and the other as 'Reason (R)'. You are to examine these two statements carefully and select the answers to these items using the codes given below.Assertion (A): For producing radiation patterns with pre-determined characteristics like beamwidth, side-lobe levels, etc. phased array antennas are widely used in antenna technologyReason (R): In a phased array antenna system the resultant radiation pattern is formed by the superposition of electromagnetic waves radiated from various antenna elements which maintain specific, pre-determined phase conditions. |
| A. | Both A and R are individually true and R is the correct explanation of A |
| B. | Both A and R are individually true but R is NOT the 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 individually true but R is NOT the correct explanation of A | |
| 53. |
A small elemental wire antenna is excited with a sinusoidal current of frequency 1 MHz. The induction field and radiation field are at equal distance d from the antenna. The value of d will be nearly |
| A. | 300 m |
| B. | 50 m |
| C. | 150 m |
| D. | 20 m |
| Answer» C. 150 m | |
| 54. |
For an observer, the redshift happens when light or other electromagnetic radiation from an object is increased in wavelength, or shifted to the red end of the spectrum. This phenomenon is due to |
| A. | Change in speed of light |
| B. | Frequency division multiple access |
| C. | Doppler Shift |
| D. | Frequency Shift Keying |
| Answer» D. Frequency Shift Keying | |
| 55. |
In a radar system, the term 'Rate-Race' is used in connection with |
| A. | Modulator |
| B. | Pulse characteristics |
| C. | Receiver Bandwidth |
| D. | Duplexer |
| Answer» E. | |
| 56. |
Consider the following statements:1. The antennas radiate energy.2. An antenna is a transition device or transducer between a guided wave and a free space wave or vice versa.3. The resonators and transmission lines store energy.4. An antenna converts electromagnetic signals to currents or vice versa.Which of these statements are correct? |
| A. | 1, 2 and 4 only |
| B. | 1, 2 and 3 only |
| C. | 2, 3. and 4 only |
| D. | 1, 2, 3 and 4 |
| Answer» B. 1, 2 and 3 only | |
| 57. |
An antenna has 40 Ω antenna resistance and 60 Ω radiation resistance. The efficiency of the antenna will be |
| A. | 30% |
| B. | 40% |
| C. | 50% |
| D. | 60% |
| Answer» E. | |
| 58. |
If the maximum effective aperture of a radiating small loop of constant current is \(\frac{3}{\left( 32\pi \right){{m}^{2}}}\), the wavelength of the radiated electromagnetic wave is: |
| A. | 5000 mm |
| B. | 100 mm |
| C. | 1000 mm |
| D. | 500 mm |
| Answer» E. | |