Description : This type of transmission permits communication in the frequency range from 30 to 60 MHz and over distances from about 1000 to 2000 km. A. Troposcatter B. Ionospheric scatter C. Ducting D. Microwave
Last Answer : B. Ionospheric scatter
Description : Type of transmission path that permits communication in the frequency range from 30 to 60 MHz and over distances form about 1000 to 2000 km. A. Ducting B. Ionospheric scatter C. Microwave D. Troposcatter
Description : What propagation condition is usually indicated when a VHF signal is received from a station over 500 miles away? A. D-layer absorption B. Faraday rotation C. Tropospheric ducting D. Moonbounce
Last Answer : C. Tropospheric ducting
Description : What propagation condition is usually indicated when a VHF signal is received from a station over 5000 miles away? A. Moonbounce B. D-layer absorption C. Tropospheric ducting D. Faraday rotation
Description : Tropospheric scatter is a method of sky wave propagation for which of the following frequency bands? A. 300 kHz to 3 MHz B. 3 MHz to 30 MHz C. 30 MHz to 300 MHz D. 300 MHz to 3 GHz
Last Answer : D. 300 MHz to 3 GHz
Description : Where is the tropospheric region that contributes most strongly to tropospheric scatter propagation?
Last Answer : Near the mid-point between the transmitting and receiving antennas, just above the radio horizon.
Description : Explain Tropospheric scatter propagation with sketch.
Last Answer : As the name implies, troposcatter uses the troposphere as the region that affects the radio signals being transmitted, returning them to Earth so that they can be received by the ... of "blurring" the overall received signal and this makes high speed data transmissions difficult.
Last Answer : Tropospheric scatter is used with frequencies in the UHF.
Description : Helical antennas are oftenused forsatellite trackingatVHFbecauseof a. troposcatter b. superrefraction c. ionospheric refraction d.theFaradayeffect
Last Answer : d.theFaradayeffect
Description : Distancesnearthe skip distance should beused forthe sky-wave propagation a. to avoid tilting b.topreventsky-wave andupper rayinterference c. to avoid the Faraday effect d. so as nor to exceed the critical frequency
Last Answer : b.topreventsky-wave andupper rayinterference
Description : Tropospheric scatteris usedwith frequenciesinthe followingrange: a. HF b. VHF c. UHF d. VLF
Last Answer : c. UHF
Description : Indicatewhich one ofthe followingterms appliestotroposcatter propagation: a. SIDs b.Fading c. Atmospheric storms d. Faraday rotation
Last Answer : b.Fading
Description : The phenomena of induced emf was observed by Faraday and Henry in: a. 1931 b. 1831 c. 1535 d. 1940
Last Answer : a. 1931
Description : Electric current produces magnetic field was suggested by: a. Faraday b. Lenz c. Ohm d. Oerested
Last Answer : c. Ohm
Description : The concept of electric field theory was introduced by: (a) Kepler (b) Newton (c) Dalton (d) Michael Faraday
Last Answer : (d) Michael Faraday
Description : Michael Faraday was known by his work on: (a) Electric force (b) Weak nuclear force (c) Strong nuclear force (d) Gravitational force
Last Answer : (a) Electric force
Description : What phenomenon causes the radio-path horizon distance to exceed the geometric horizon? A. Diffraction B. Ducting C. Reflection D. Refraction
Last Answer : D. Refraction
Description : As electromagneticwavestravelinfree space, onlyone ofthefollowingcan happento them: a. absorption b. attenuation c. refraction d. reflection
Last Answer : b. attenuation
Description : .In electromagneticwaves,polarization a. is caused by reflection b.isdue to the transversenature ofthewaves c. results from the longitudinal nature of the waves d. is always vertical in an isotropic medium
Last Answer : b.isdue to the transversenature ofthewaves
Description : Which of the following phenomena provides a convincing proof for wave nature of radiation a) Reflection b) Refraction c) Polarization d) Interference and diffraction
Last Answer : d) Interference and diffraction
Description : Find false statement about effect of sulphur in fuel? (A) It has heating value (B) It helps in electrostatic precipitation of ash in flue gases (C) It leads to corrosion of air heaters, ducting, etc. if flue gas exit temperature is low (D) It erodes furnace walls
Last Answer : (D) It erodes furnace walls
Description : The angle of elevation of the antenna beam is 20°. Calculate the transmission-path distance for an ionospheric transmission that utilizes a layer of virtual height 200 km. Use flat-earth approximation. A. 966 km B. 2100 km C. 1100 km D. 405 km
Last Answer : C. 1100 km
Description : Thehigherthe index number a. the higher the speed of light b. the lower the speed of light c. has no effect on the speed of light d. the shorter the wavelength propagation
Last Answer : a. the higher the speed of light
Description : Thevelocityfactor of a transmissionline a. depends on the dielectric constant of the material used b. increases the velocity along the transmission line c. is govern by the skin effect d. is higher for a solid dielectric than for air
Last Answer : a. depends on the dielectric constant of the material used
Description : The reverse process of photo-electric effect is called: a) Annihilation of matter b) Compton effect c) Pair production d) X-rays
Last Answer : d) X-rays
Description : The continuous X-ray spectrum is obtained due to the effect called a) Braking radiation b) Bremsstrahlung c) both a & b d) none of a & b
Last Answer : b) Bremsstrahlung
Description : Which one of the following phenomena can be studied with -rays a) Photoelectric effect b) Compton effect c) Pair production d) All of the above
Last Answer : a) Photoelectric effect
Description : A device based on photo electric effect is called a) Photo sensitive b) Photo diode c) Photo synthesis d) Photo cell
Last Answer : d) Photo cell
Description : Photoelectric effect was discovered by a) Einstein b) G.P.Thomson c) Hallwachs d) Lenard
Last Answer : a) Einstein
Description : In forward bias, the width of potential barrier __________ (a) Increases (b) decreases (c) remains same (d) no effect
Last Answer : (b) decreases
Description : What ionospheric layer has a daytime approximate critical frequency of 8 MHz? A. F2 layer B. F1 layer C. E layer D. D layer
Last Answer : A. F2 layer
Description : What height of an ionized layer is determined from the time interval between the transmitted signal and the ionospheric echo at vertical incidence? A. Virtual height B. Apparent height C. Actual height D. Effective height
Last Answer : A. Virtual height
Description : What is the refractive index of an ionospheric layer with 100x105 free electrons per m3 ? Assume frequency to be at 20 MHz. A. 0.99 B. 0.15 C. 0.78 D. 0.85
Last Answer : A. 0.99
Description : Where does the greatest amount of ionospheric absorption occur in the ionosphere?
Last Answer : Where ionization density is greatest.
Description : Explain ionospheric propagation with neat sketch. Explain two properties of layers of ionosphere.
Last Answer : Diagram : Explanation: The transmitted signal travels into the upper atmosphere where it is reflected back to earth due to the presence of layers called as ionosphere in the upper ... having highest electron density of all layers, due to this F2 layer remains present at night time.
Description : What antenna can be used to minimize the effect of Faraday rotation of polarization? A. Dipole B. Parabolic C. Helical D. Rhombic
Last Answer : C. Helical
Description : The temperature most suited for con- ducting an industrial process involving a re- versible reactions; most conveniently and profitably is called?
Last Answer : Optimum temperature
Description : What do you call the increase of temperature with height? A. Temperature inversion B. Normal inversion C. Ducting D. Superrefraction
Last Answer : A. Temperature inversion
Description : Maximum Differential pressure: a. Is the maximum authorized pressure difference between the inside of the fuselage and the atmospheric ambient pressure b. Is the absolute pressure provided by the vacuum ... time limit d. Is the absolute pressure the cabin pressure ducting is designed to carry
Last Answer : a. Is the maximum authorized pressure difference between the inside of the fuselage and the atmospheric ambient pressure
Description : Maximum Differential pressure: a. Is the maximum authorized pressure difference between the inside of the fuselage and the atmospheric ambient pressure b. Is the absolute pressure provided by the ... time limit d. Is the absolute pressure the cabin pressure ducting is designed to carry
Description : Indicatewhich one ofthe followingreasonsforthe use of a groundscreenwith antennasisfalse: a. Impossibility of a good ground connection b. Provision of an earth for the antenna c.Protectionofpersonnelworkingunderneath d. Improvement of the radiation pattern of the antenna
Last Answer : c.Protectionofpersonnelworkingunderneath
Description : Indicatewhich ofthe followingreasonsfor usinga counterpoisewith antenna isfalse: a. Impossibility of a good ground connection b.Protectionofpersonnelworkingunderground c. Provision of an earth for the antenna d. Rockiness of the ground
Last Answer : b.Protectionofpersonnelworkingunderground
Description : What is the difference between neutral and earth?
Last Answer : The ground or "earth" wire is a circuit's safety protective wire that normally carries no current.
Description : If you get an earth fault alarm what will you do?
Last Answer : The fault can be investigated by first identifying areas of ship that have a high chance of earth fault (example deck lighting or pantry equipment) and then switching off their supplies one at a time to see ... the alarm, we know that that circuit is having earth fault and we can go and repair it.
Description : What is the purpose of the earth fault indication on the switch board?
Last Answer : It detects and indicates phase to earth fault on a circuit.
Description : The gas which was identified in the Sun using spectroscopy before its discovery on earth, is a) oxygen b) hydrogen c) helium d) nitrogen
Last Answer : c) helium
Description : (1) the action of ultraviolet rays on oxygen Explanation: The majority of tropospheric ozone formation occurs when nitrogen oxides (NOx), carbon monoxide (CO ) and volatile organic compounds (VOCs), such as xylene, ... violet rays. NOx, CO, and VOCs are called ozone precursors. CO + 2O2 + CO2 + O3
Last Answer : Water is not effective in extinguishing a fire caused by petrol because - (1) the flame is too hot for water to cool it down (2) water and petrol react chemically (3) water and petrol are ... (4) water and petrol are immiscible with each other and petrol which forms the upper layer continues to burn
Description : ____ is a term given to the region where superrefraction occurs. A. Strata B. Duct C. Isothermal region D. Tropospheric region
Last Answer : B. Duct