extinction coefficient

[pinkypig]

but i don't understand how to work out Ka?

[pinkypig]

what are the units for the extinction coefficient?

[pinkypig]

i need help again!i have drawn the graph and evrything got the gradient etc but it seems asif i'v got all the figures for the equation: Abs=e*b*c
so now i don't know what part of the equation i'm tryin to work out because when c = 2 Abs= 0.09 , b= 1 and e = 0.0425