For the safety and comfort of factory workers, the sound-intensity level in a certain factory
must remain below 85 dB. What is the maximum sound intensity allowed in this factory?
A. 3.2 x 10-4 W/m2
B. 3.2 x 10-6 W/m2
C. 3.2 x 10-10 W/m2
D. 3.2 x 10-3 W/m2

1 Answer

Answer :

A. 3.2 x 10-4 W/m2

Related questions

Description : The sound intensity received from the nearby jet plane is 12.6 µW/m2 and that from another jet plane some distance away is 0.45 µW/m2 . Find the relative loudness of the two. A. 14.0 dB B. 14.5dB C. 12.5 D. 14.5

Last Answer : B. 14.5dB

Description : A choir consisting of 36 individuals all of whom can sing with the same intensity. A soloist sings a certain passage and then is joined by the remainder of the choir members for a repeat of the passage. What is the ... sound intensity level in the two cases? A. 3 dB B. 6 dB C. 36 dB D. 15.6dB

Last Answer : D. 15.6dB

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 sound intensity corresponds to a sound-intensity level of 50dB? A. 1 x 10-6W/m2 B. 1 x 10-7W/m2 C. 1 x 10-8W/m2 D.1 x 10-5W/m2

Last Answer : B. 1 x 10-7W/m2

Description : The sound power level of a jet plane flying at a height of 1 km is 160 dB. What is the maximum sound pressure level on the ground directly below the plane assuming that the aircraft radiates sound equally in all directions? A. 59.1 dB B. 69.1 dB C. 79.1 dB D. 89.1 dB

Last Answer : D. 89.1 dB

Description : What increase in sound level is commonly perceived by most people? A. 6 to 10 dB B. 1 to 3 dB C. 3 to 6 dB D. 10 to 20dB

Last Answer : A. 6 to 10 dB

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 : The ordinary and maximum tolerance limit of sound by human being is – (1) 50 db to 70 db (decibel) (2) 60 db to 80 db (decibel) (3) 65 db to 75 db (decibel) (4) 70 db to 85 db (decibel)

Last Answer : (2) 60 db to 80 db (decibel) Explanation: Normal speech is about 60 dB (decibels). A dangerous sound is anything that is 80 dB or higher which can lead to hearing loss. At 70 dB or ... the risk of harm to healthy ears is negligible. Listening to sound above 80 decibels can cause profound deafness.

Description : The ordinary and maximum tolerance limit of sound by human being is (1) 50 db to 70 db (decibel) (2) 60 db to 80 db (decibel) (3) 65 db to 75 db (decibel) (4) 70 db to 85 db (decibel)

Last Answer : 60 db to 80 db (decibel)

Description : Cable attenuation is usually expressed in terms of a. Loss per foot b. dB/km c. intensity per mile d. voltage drop per inch

Last Answer : b. dB/km

Description : Sound intensity level is ________. A. 10 log I/I(ref) B. 10 log I(ref)/I C. 30 log I/I(ref) D. 20 log I/I(ref)

Last Answer : A. 10 log I/I(ref)

Description : The approximate intensity level of the sound which can caused damage to the ear drum is _____? A. 100 dB B. 60 dB C. 160 dB D. 20 dB

Last Answer : ANSWER: A

Description : The approximate intensity level of the sound which can cause damage to the ear drum is? A. 20 dB B. 60 dB C. 100 dB (Answer) D. 160 dB

Last Answer : C. 100 dB (Answer)

Description : For a loudness level between 110 and 120 dB, the maximum daily exposure limit is ____ minute (s). A. 1 B. 60 C. 20 D. 45

Last Answer : A. 1

Description : What is the effective radiated power of a repeater with 120 watts transmitter power output, 5 dB feedline loss, 4 dB duplexer and circulator loss, and 6 dB antenna gain? A. 601 W B. 240 W C. 60 W D. 379 W

Last Answer : C. 60 W

Description : What is the effective radiated power of a repeater with 75 watts transmitter power output, 5 dB feedline loss, 4 dB duplexer and circulator loss, and 6 dB antenna gain? A. 37.6 W B. 237 W C. 150 W D. 23.7 W

Last Answer : A. 37.6 W

Description : What is the effective radiated power of a repeater with 50 watts transmitter power output \, 4 dB feedline loss, 3 dB duplexer and circulator loss, and 6 dB antenna gain? A. 158 W B. 39.7 W C. 251 W D. 69.9 W

Last Answer : B. 39.7 W

Description : What is considered the threshold of audibility at 3000 Hz? A. 10-12 W/m2 B. 10-16 W/m2 C. 10-12 W/cm2 D. 10-15 W/cm2

Last Answer : A. 10-12 W/m2

Description : What is the effective radiated power of a repeater with 200 watts transmitter power output, 4 dB feline loss, 4 dB duplexer and circulator loss, and 10 dB antenna gain? A. 317 W B. 2000 W C. 126 W D. 260 W

Last Answer : A. 317 W

Description : What is the effective radiated power of a repeater with 100 watts transmitter power output, 5 dB feedline loss, 4 dB duplexer and circulator loss, and 10 dB antenna gain? A. 800 W B. 126 W C. 12.5 W D. 1260 W

Last Answer : B. 126 W

Description : What is the effective radiated power of a repeater with 75 watts transmitter power output, 4 dB feedline loss, 3 dB duplexer and circulator loss, and 10 dB antenna gain? A. 600 W B. 75 W C. 18.75 W D. 150 W

Last Answer : D. 150 W

Description : Part of a microwave link can be approximated by free space conditions. The antenna gain are each 40 dB, the frequency is 10 GHz, and the path length is 80 km. Calculate the receive power for a transmitted power of 10 W? A. 0.871 μW B. 871 μW C. 0.871 mW D. 871 nW

Last Answer : A. 0.871 μW

Description : A properly matched transmission line has a loss of 1.5 dB/100m. if 10 W is supplied to one end of the line, how many watts reach the load, 27 m away? A. 10 W B. 7.2 W C. 9.9 W D. 9.1 W

Last Answer : D. 9.1 W

Description : You are measuring noise at a -6 dB level point, using the Lenkurt 601A, F1A weighting network, and a flat meter. The meter reading is -59 dBm. This is _________ dBa0. A. 24 B. 12 C. 23 D. 32

Last Answer : D. 32

Description : What is the intensity of sound in normal conversation? (a) 10-20 dB (b) 30-60 dB (c) 70-90 dB (d) 120-150 dB

Last Answer : b) 30-60 dB

Description : At a distance of 10 meters form a point source, the intensity level is measured to be 70 dB. At what distance form the source well the intensity be 40 dB? How do you solve this?

Last Answer : Going on memory here….3db is half the intensity. The intensity is usually inversely proportional to r squared. The rest is math, so 70–40 is 30 or ten halves.

Description : What is the effective radiated power of a repeater with 50 watts transmitter power output, 5 dB feedline loss, 4 dB duplexer and circulator loss, and 7 dB antenna gain? A. 300 W B. 315 W C. 31.5 W D. 69.9 W

Last Answer : C. 31.5 W

Description : ECE Board Exam March 1996 The power of standard test tone is normally ____________. A. 1 dB B. 0 mW C. 1 mW D. 1 W

Last Answer : C. 1 mW

Description : What is the gain of an antenna over a half-wavelength dipole when it has 6 dB gain over an isotropic radiator? A. 6.0 dB B. 8.1 dB C. 3.9 dB D. 10.0 dB

Last Answer : C. 3.9 dB

Description : Determine the dB gain of a receiving antenna which delivers a microvolt signal to a transmission line over that of an antenna that delivers a 20 microvolt signal under identical circumstances. A. 10 dB B. 6 dB C. 3 dB D. 8 dB

Last Answer : B. 6 dB

Description : What is the gain of four identically polarized antennas stacked one above the other and fed in phase? A. 3 dB over the gain of one antenna B. 10 dB over the gain of one antenna C. 4 dB over the gain of one antenna D. 6 dB over the gain of one antenna

Last Answer : D. 6 dB over the gain of one antenna

Description : The upper safe noise level for machine operator is: A. 85 db B.100db C. 110db D.115db

Last Answer : A. 85 d

Description : At what power level does a 1 KHz tone cause zero interference (144 weighted)? A. 90 dB B. 90 dBm C. -90 dBm D. -90 dBm

Last Answer : D. -90 dBm

Description : Your Western Electric 3A test set meter reading is -23 dBm at at test point level of -8 dB. This is ______ dBrnc0. A. 75 B. 29 C. 30 D. 31

Last Answer : A. 75

Description : You are measuring noise at a +3 dB level point, using the Lenkurt 601A, F1A weighting network, and a flat meter. The meter reading is -57dBm. This is ________dBa0. A. 20 B. 15 C. 25 D. 17

Last Answer : C. 25

Description : What is the required quality factor for an SSB filter with the following data: center frequency= 1 MHz, the desired attenuation level of the unwanted sideband= 80 dB and the separation between sidebands= 200 Hz? A. 1,250 B. 12,500 C. 125,000 D. 25,000

Last Answer : C. 125,000

Description : What loudness level in which permanent damage to hearing is possible? A. 120 dB B. 140 dB C. 130 dB D. 150 dB

Last Answer : D. 150 dB

Description : At what loudness level do pitch (in mels) and frequency (in Hz) are numerically equal? A. 0 dB B. 20 dB C. 60 dB D. 40 dB

Last Answer : D. 40 dB

Description : You are measuring noise in a voice channel at 7 dB test point level. The meter reads -56 dBm (FIA weighted). What is the reading in dBrnc? A. 20 B. 32 C. 35 D. 25

Last Answer : C. 35

Description : You are measuring a voice channel at a -4 dB test point level, the meter reads -73 dBm (pure test tone) convert the reading in dBmCO. A. 16 B. 18 C. 22 D. 12

Last Answer : C. 22

Description : Which stands for dB relative level? A. dBrn B. dBm C. dBr D. dBa

Last Answer : C. dBr

Description : In measuring noise in a voice channel at a 4 dB test point level, the meter reads -70 dBm (F1A weighted), convert the reading to pWp. A. 53 B. 93 C. 63 D. 83

Last Answer : B. 93

Description : ECE Board Exam March 1996 At what power level does a 1 kHz tone cause zero interference (144 weighted) ? A. -90 dB B. -90 dBm C. 90 dBm D. 90 dB

Last Answer : B. -90 dBm

Description : The pressure intensity in kN/m2 (or kPa) at any point in a liquid is (where w = Specific weight of liquid, and h = Depth of liquid from the surface) (A) w (B) wh (C) w/h (D) h/w

Last Answer : Answer: Option B

Description : The intensity of active earth pressure at a depth of 10 metres in dry cohesionless sand with an angle of internal friction of 30° and with a weight of 1.8 t/m3 , is (A) 4 t/m2 (B) 5 t/m2 (C) 6 t/m2 (D) 7 t/m2

Last Answer : Answer: Option C

Description : What is the reference tone level for dBa? A. -90 dBm B. -82 dBm C. -67 dBm D. -85 dBm

Last Answer : D. -85 dBm

Description : What is the reference tone level for dBrn? A. -90 dBm B. -82 dBm C. -67 dBm D. -85 dBm

Last Answer : A. -90 dBm

Description : What is the reference level for noise measurement, F1A weighted? A. -90 dBm B. -82 dBm C. -67 dBm D. -85 dBm

Last Answer : D. -85 dBm

Description : ECE Board Exam March 1996 What is the reference tone level for dBm? A. -82 dBm B. -85 dBm C. -67 dBm D. -90 dBm

Last Answer : D. -90 dBm