waec model questions vol1 2021 physics
Objective • Question 19
Question 19
WAEC_MODEL_QUESTIONS_VOL1
•
2021
A loudspeaker emits sound uniformly in air. At a distance of 5 m from the speaker the intensity level is measured as 90 dB. The atmospheric absorption coefficient for the sound is 0.005 dB m⁻¹. Assuming spherical spreading of the sound, determine the intensity level (in dB, to one decimal place) at a distance of 20 m from the speaker, taking both spherical spreading and atmospheric absorption into account.
Answer Options
A.
73.5
B.
71.0
Correct Answer
C.
77.9
D.
80.2
Correct Answer
C
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