A certain sound source is increased in sound level by 30db by how many multiples its intensity is increased
Answers
Similar ans from book.... just change the values. I have not enough time to answer immediately.
The intensity level B of the sound is defined as follows:
B
=
(
10
d
B
)
×
log
I
I
o
H
e
r
e
,
∙
I
: intensity of the sound
∙
I
o
: intensity of the reference level
(a) Let the original sound intensity level be
B
1
and the the increased sound intensity level be
B
2
. Then, the corresponding intensities are
I
1
and
I
2
. When the intensity level increases by 120 dB,
B
2
−
B
1
=
(
10
d
B
)
log
I
2
I
o
−
(
10
d
B
)
log
I
1
I
o
=
(
10
d
B
)
log
I
2
I
1
=
120
d
B
So, we can find the ratio between the intensities:
log
I
2
I
1
=
120
10
=
12
After rearranging the above equation, we find
I
2
=
I
1
×
10
12
That is, the intensity is increased by
10
12
.
(b) In general, the intensity I is proportional to the square of the pressure amplitude P. In other words,
P
∝
√
I
So, if the intensity is increased by
10
12
, the pressure amplitude is increased by
10
6
.