Description : In the above problem, what is the new velocity of sound assuming dry air medium? A. 343 ft/s B. 3430 m/s C. 343 m/s D. 342 m/s
Last Answer : C. 343 m/s
Description : If temperature change is 19°C, what amount of change to sound velocity is possible? A. 11.53 ft/s B. 11.53 m/s C. 19.304 ft/s D. 19.304 m/s
Last Answer : B. 11.53 m/s
Description : ECE Board Exam March 1996 A car horn outdoors produces a sound intensity level of 90 dB at 10 ft away. At this distance, what is the sound power in watt? A. 12 W B. 0.12 W C. 0.012 W D. 1.2 W
Last Answer : C. 0.012 W
Description : What is the physical length of the above transmission line at 3/8λ long? A.0.82 m B. 0.82 ft C. 0.82 in D. 0.82 cm
Last Answer : B. 0.82 ft
Description : If the operating frequency is 450 MHz what length of a pair of conductors is considered to be a transmission line? A. 2.19 ft B. 2.19 m C. 0.219 ft D. 0.219 m
Last Answer : C. 0.219 ft
Description : Calculate the reverberation time of a living room 8 ft high, 13 ft wide and 20 ft long. The total absorption of the building structure inside the room is 180.7 sabines with four persons present in the room. A. 0.5 ms B. 0.05 s C. 0.5 s D. 5 ms
Last Answer : C. 0.5 s
Description : ____________ is the average rate of transmission of sound energy in a given direction through a cross sectional area of 1 sq.m. at right angle to the direction. A. Sound pressure B. Sound intensity C. Pressure variation D. Loudness
Last Answer : B. Sound intensity
Description : A vertical column of water will be supported to what height by standard atmospheric pressure. If the Y w = 62.4lb/ft3 po = 14.7 psi. a. 44.9 ft b. 33.9 ft c. 22.9 ft d. 55.9 ft formula: ho= po/Yw
Last Answer : 33.9 ft
Description : A vertical column of water will be supported to what height by standard atmospheric pressure. a. 33.9 ft b. 45 ft c. 67 ft d. 25.46 ft ho= Po/Yo
Description : What is the velocity of sound in wood? A. 5800 m/s B. 5000 m/s C. 3300 m/s D. 3700 m/s
Last Answer : C. 3300 m/s
Description : What is the velocity of sound in wood (m/s)? A. 330 B. 3600 C. 3300 D. 5800
Last Answer : C. 3300
Description : ECE Board Exam March 1996 Atmospheric condition is controlled by A. humidity B. pressure C. temperature D. all of these
Last Answer : D. all of these
Description : What is the approximate weight in pounds of the atmosphere on a 1 sq. ft. surface at sea level? w) 15 lbs. x) 1500 lbs. y) 2100 lbs. z) 20,000 lbs.
Last Answer : ANSWER: Y -- 2100 LBS.
Description : What is the approximate path loss from satellite-to-earth station? A. 100 dB B. 150 dB C. 175 dB D. 200 dB
Last Answer : D. 200 dB
Description : What is the approximate intensity of the magnetic field at the earth’s surface? A. 32,000 nT B. 62,000 nT C. 32,000 µT D. 62,000 µT
Last Answer : A. 32,000 nT
Description : What is the approximate bandwidth of an FM system with 10 kHz of modulating frequency and a 150 kHz of frequency deviation? A. 300 kHz B. 320 kHz C. 150 kHz D. 200 kHz
Last Answer : B. 320 kHz
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 is the approximate single-hop nighttime range of F2 layer? A. 3840 km B. 3000 km C. 4130 km D. 2350 km
Last Answer : C. 4130 km
Description : What is the approximate critical frequency of the E layer? A. 4 MHz B. 5 MHz C. 6 MHz D. 3 MHz
Last Answer : A. 4 MHz
Description : The approximate single-hop nighttime range of F2 layer is ____. A. 3000 km B. 3840 km C. 4130 km D. 2350km
Description : During the night when the F2 layer combines with F1 layer it falls to what approximate height? A. 250 km B. 350 km C. 300 km D. 400 km
Last Answer : C. 300 km
Description : What is the approximate percentage of earth coverage of a geostationary satellite at zero degree elevation? A. 33.3% B. 45.2% C. 42.5% D. 30.5%
Last Answer : C. 42.5%
Description : Which of the cable length has the highest attenuation? a. 1 km b. 2 km c. 95 ft d. 5500 ft
Last Answer : b. 2 km
Description : The length of a Marconi antenna to operate with 985 kHz is ______. A. 200 ft B. 500 ft C. 250 ft D. 999 ft
Last Answer : C. 250 ft
Description : The noise from an airplane engine 100 ft from an observer is found to have an intensity of 45dB. What will be the intensity when the plane flies overhead at an altitude of 1 mi? A. 10.5 dB B. 34.5 dB C. 35 dB D. 20.5 dB
Last Answer : A. 10.5 dB
Description : Find the equivalent inductance per foot of the above cable? A. 13.5 nF/ft B. 13.5 pF/ft C. 116.8 nH/ft D. 116.8 pF/ft
Last Answer : C. 116.8 nH/ft
Description : What is the time delay introduced by a 75-ft coaxial cable with a dielectric constant of 2.3? A. 1.54 ns B. 11.5 ns C. 115.6 ns D. 1156 ns
Last Answer : C. 115.6 ns
Description : What is transit time (time delay) of a 50-ft length transmission line of the above problem? A. 50 ns B. 100 ns C. 75 ns D. 65 ns
Last Answer : C. 75 ns
Description : What is the velocity factor of coaxial cable with a characteristic impedance of 50Ω and capacitance of 30pF/ft and inductance of 75 nH/ft? A. 0.58 B.0.68 C. 0.98 D. 0.81
Last Answer : B.0.68
Description : What is the maximum line-of-sight distance between a paging antenna 250 ft high and a pager receiver 3.5ft of the ground? A. 25 km B.25mi C. 70.73 km D. 70.73 mi
Last Answer : B.25mi
Description : Determine the gain of a 6 ft. parabolic dish operating at 1800 MHz. A. 30 dB B. 11.2 dB C. 15.5 dB D. 28.17 dB
Last Answer : D. 28.17 dB
Description : The speed of light is a. 186,000 mi/h b. 300 mi/h c. 300,000 m/s d. 300,000,000 m/s
Last Answer : d. 300,000,000 m/s
Description : Which of the following factor does not harm laser efficiency? a. Atmospheric absorption b. Excitation energy not absorbed c. Problems in depopulating the lower laser level d. Inefficiency in populating the upper laser level
Last Answer : a. Atmospheric absorption
Description : Is a loss of power of a satellite downlink signal due to earth’s atmosphere. A. Atmospheric loss B. Path loss C. Radiation loss D. RFI
Last Answer : B. Path loss
Description : The major cause of atmospheric or static noise are A. Thunderstorms B. Airplanes C. Meteor showers D. All of these
Last Answer : A. Thunderstorms
Description : What is the primary cause of atmospheric noise? A. Thunderstorm B. Lightning C. Thunderstorm and lightning D. Weather condition
Last Answer : B. Lightning
Description : Indicate the noise whose sources are in category different from that of the other three? A. Solar noise B. Cosmic noise C. Atmospheric noise D. Galactic noise
Last Answer : C. Atmospheric noise
Description : Atmospheric noise becomes less severe at frequencies A. above 30 MHz B. below 30 MHz C. above 3000 kHz D. below 3000kHz
Last Answer : A. above 30 MHz
Description : Atmospheric noise or static is not a great problem A. at frequencies below 20 MHz B. at frequencies below 5 MHz C. at frequencies above 30 MHz D. at frequencies above 1 MHz
Last Answer : C. at frequencies above 30 MHz
Description : Atmospheric noise is known as _______noise. A. static B. cosmic C. solar D. lunar
Last Answer : A. static
Description : Which noise is produced by lighting discharges in thunderstorms? A. White noise B. Extraterrestrial noise C. Industrial noise D. Atmospheric noise
Last Answer : D. Atmospheric noise
Description : _________ is measured on a circuit when it is correctly terminated but does not have any traffic. A. White noise B. Galactic noise C. Impulse noise D. Atmospheric noise
Last Answer : A. White noise
Description : What do you call the random noise seen on radar display screen? A. Impulse noise B. Atmospheric noise C. Grass D. Johnson noise
Last Answer : C. Grass
Description : Atmospheric attenuation is an attenuation which is due to A. mist and fog B. gasses in the atmosphere C. water vapor and oxygen D. rain
Last Answer : C. water vapor and oxygen
Description : What noise is observable at frequencies in the range from about 8 MHz to somewhat 1.5 GHz? A. Industrial noise B. Atmospheric noise C. Space noise D. Shot noise
Last Answer : C. Space noise
Description : The band of frequencies least susceptible to atmospheric noise and interference is: A. 30 – 300 kHz B. 300 – 3000 kHz C. 3 – 30 MHz D. 300 – 3000 MHz
Last Answer : D. 300 – 3000 MHz
Description : What is the major cause of atmospheric or static noise? A. Sunspots B. Airplanes C. Meteor showers D. Thunderstorm
Last Answer : D. Thunderstorm
Description : Atmospheric noise is less at severe frequencies above A. Audio level B. 30 MHz C. 10 GHz D. 1 GHz
Last Answer : B. 30 MHz
Description : Which is atmospheric attenuation? A. Attenuation due to rain B. Attenuation due to other gasses C. Attenuation due to mist and fog D. Due to water vapor and oxygen
Last Answer : D. Due to water vapor and oxygen