A sound wave of wavelength `20pi` cm travels in air if the difference between the maximum and minimum pressures at a given point is `3.0xx10^-3 N//m^2`.
Now sound level is increased by 20 dB, if the new amplitude of vibration of the particles of the medium at that given point is 20k (in `Å`) then 'k' is : (The bulk modulus of air is `1.5xx10^5 N//m^2`) (wavelength is same in both cases )

Explanation

Sound level in dB is `B=10 log_10(I/I_0)`
If `B_1 and B_2` are the sound levels and `I_1 and I_2` are the intenaities in the two cases.
`B_2-B_1= 10 log_10 (I_2/I_1)`
`I_2/I_1=100` So `S_(02)/S_(01)=sqrt(I_2/I_1)=10`
`S_(02)=10 S_(01)`
and `S_(01)=P_0/(BK)=3/2xx10^-3/(1.5xx10^5)xx(20pixx10^(-2))/(2pi)=10A`
So `S_(02)=100Å`