beta=10log_10 (I/10^-16)=10log_10(10^16I)β=10log10(I10−16)=10log10(1016I).
Using the Usual Rules of loglog functions,
beta=10{log_10 10^16+log_10I}β=10{log101016+log10I},
=10{16log_10 10+log_10 I}=10{16log1010+log10I},
=10{16+log_10 I}=10{16+log10I}.
=160+10log_10I=160+10log10I.
Here, by the Change of Base Rule, log_10I=lnI/ln10log10I=lnIln10
rArr beta=160+10/ln10*lnI....................(ast).
Now, the reqd. rate=[(dbeta)/(dI)]_(I=10^-4)
From (ast), (dbeta)/(dI)=0+10/ln10*1/I.
:."The Reqd. Rate"=[10/ln10*1/I]_(I=10^-4),
=10/ln10*1/10^-4,
=10^5/ln10.