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Correct CHOICE is (a) \(ϵ’=ϵ+\frac{σ}{jw} \)

The EXPLANATION is: The earth is neither a GOOD conductor nor a good DIELECTRIC. So the dielectric constant of earth is complex and is given by\(ϵ’=ϵ+\frac{σ}{jw} \)where σ is the conductivity and W is angular frequency.

The CORRECT choice is (a) \(γ_r=\frac{η_2-η_1}{η_2+η_1} \)

The best I can explain: The reflection FACTOR is GIVEN by the ratio of Reflected wave to incident wave.

\(ρ=\frac{reflected\, wave}{incident\, wave}=\frac{E_r}{E_i} \)

Reflection coefficient of plane waves with NORMAL INCIDENCE in terms of impedances of medium is \(γ_r=\frac{η_2-η_1}{η_2+η_1} \)

Correct choice is (a) γr= γt-1

To EXPLAIN: Relation between TRANSMISSION coefficientγt and reflection coefficient is γr is γr = γt – 1

Transmission coefficient is the ratio of transmitted to incident wave. The reflection FACTOR is given by the ratio of Reflected wave to incident wave.

Correct answer is (d) both on the power radiated by the transmitting antenna & directivity in VERTICAL and horizontal PLANES

Explanation: The field STRENGTH E0 of the wave at a unit DISTANCE from transmitting antenna depends on both on the power radiated by the transmitting antenna & directivity in vertical and horizontal planes. The overall field strength is calculated from this. The field strength of the SURFACE wave of flat earth is given by E=AE0/d.

Correct CHOICE is (a) 2MHz

The BEST I can explain: Ground wave PROPAGATION also KNOWN as surface wave propagation is used up to 2MHz. sky wave propagation is used at 2MHz to 30MHz.

Right answer is (a) Ground wave

The best explanation: Ground wave PROPAGATION is used for signals up to frequency of 2MHz. It is useful for the broadcast and low frequency signals. Space waves are ALSO KNOWN as tropospheric waves useful for FM reception. Sky wave propagation is used for long DISTANCE communication.

Right answer is (a) E=AE0/d

To explain I would say: The field strength of the surface wave of flat earth is given by E=AE0/d, here A is the ground attenuation FACTOR, d is the distance and E0 is the field strength PER UNIT distance. The field strength of the wave at a unit distance from transmitting antenna depends on both on the power radiated by the transmitting antenna & directivity in VERTICAL and horizontal PLANES

The correct choice is (c) F2 layer

The BEST I can explain: F2 layer is formed by the ionization of the UV, x-rays and corpuscular radiations. F1 is formed by the ionization of O2 atoms. F layer is the top layer in the ionosphere and has highest ELECTRON density. D layer is due to PHOTO ionization of O2 atoms at first level.

The CORRECT answer is (b) F1 layer

The best I can explain: Only F1 layer follows the CHAPMAN’s law of VARIATION where F1 region behaves LIKE an E-region. F1 layer is formed by the IONIZATION of O2 atoms. F2 layer does not follow Chapman’s law of variation.

Correct choice is (a) Temperature decreases with INCREASE in height

Best EXPLANATION: The property of troposphere is that temperature decreases with increase in height. Gas components REMAINS in constant PERCENTAGE with increase in height but water vapor components DECREASE with increase in height.

Right choice is (b) False

Explanation: Ionospheric reflections in the shape of M –type OCCURS between Es (LAYER formed due to the ions of clouds, thunderstorms etc) and higher F layers if the layers are SMALLER COMPARED to the wavelengths. These M-type reflections take a single PATH in E layer.

Right OPTION is (a) Troposphere

To explain: Troposphere is the lowest layer in the ATMOSPHERE ranging up to 15KM. stratosphere lies at 50 to 90km and up to 400km ionosphere. Above 400km is the outer atmosphere.

The correct choice is (a) 3/4

For explanation I WOULD SAY: Effective radius of earth is the EQUIVALENT radius of earth used to correct atmospheric refraction as the refractive INDEX VARIES linearly with height. It is 4/3 times the geometrical radius of the earth.

Correct choice is (a) Increases

To explain I would say: GROUND wave propagation is used at below 2MHz frequency. Ground wave propagation is used for short distance. By using sufficient power and low frequencies it can be used EFFECTIVELY. Ground wave losses increase RAPIDLY with frequencies.

The correct answer is (a) 2MHz

The explanation is: Ground wave PROPAGATION is used for SIGNALS up to frequency of 2MHz. Ground WAVES are vertically polarized and transmitting and receiving antennas are placed closely and the wave follows the curvature of the EARTH.

Right choice is (c) F2 LAYER

The explanation: The electron /ION density INCREASES with the increase in height in IONOSPHERE. F2 layer has 3×10^5 to 2×10^6electron density . F2 layer = 2×10^5to 4.5×10^5

Correct choice is (c) IONOSPHERE

Easiest explanation: In ionosphere ionization OCCURS so there are free electrons, positive and negative ions are ALSO PRESENT. It is at 110- 400km range from earth surface.

The correct choice is (a) D LAYER

Easy EXPLANATION: D layer is present at 70km from the EARTH SURFACE and is the nearest layer to earth surface. E layer lies at 110km, f1 layer at 220km and F2 at 250 to 400km. Based on the density of ions different LAYERS are present in this layer.