Luminosity and Apparent Magnitude

In message , Robert
writes
Ok, so the brightness of a star is supposed to be proportional to the
luminosity / distance squared.

If a star's luminosity suddenly increases by 600 then the apparent magnitude
should be +600 (since the distance is unchanged), right?

Yet apparently the correct answer is that the apparent magnitude decreases
by 7. Can someone please 'splain?

Thanks.


Magnitude is a logarithmic scale, not a linear one, and is defined such
that brighter objects have lower magnitudes. A decrease of 5 magnitudes
is defined as a 100-fold increase in brightness, i.e. 1 magnitude
corresponds to a factor of approximately 2.512 in brightness.
--
Stewart Robert Hinsley