AAMC cbt 10 #50

[kabtq9s]

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First of all I don't fully understand the question, is it asking us to find an Intesnity from the given decibels then subtract it from another intensity ?

Secondly is there a way to solve this problem by just using the orange text and table that I memorized from examKrackers 😛 ?


Thanks in advance

 

[Jepstein30]

First of all I don't fully understand the question, is it asking us to find an Intesnity from the given decibels then subtract it from another intensity ?

Secondly is there a way to solve this problem by just using the orange text and table that I memorized from examKrackers 😛 ?


Thanks in advance

Its just asking you for I when the dB level is 120. No, orange text won't help you because it's not asking about dB levels.. they gave you the equation for a reason.

Plug and chug.

Intensity = 10 log (x/Io)
120 = 10 log (x/10^-12)
12 = log (x/10^-12)
10^12 = (x/10^-12)
x = 10^-12 * 10^12 = 1 or 10^0

 

[Singhp03]

check out this web page, it really helps clarifies how intensity is expressed in the decibel scale:http://www.physicsclassroom.com/class/sound/u11l2b.cfm

 

[sciencebooks]

First of all I don't fully understand the question, is it asking us to find an Intesnity from the given decibels then subtract it from another intensity ?

Secondly is there a way to solve this problem by just using the orange text and table that I memorized from examKrackers 😛 ?


Thanks in advance

You understood that 120 decibels was related to 10^12. 10^12 should be the intensity RATIO. So solve X/(10^-12)=10^12