set ylabel "Ladung [C]"
set xlabel "Ausschlag [mm]"

set term postscript enhanced eps fontfile './cmunrm.pfb' "CMUSerif-Roman" 21
set output "galvanometer.eps"

set size 0.9,0.9

C = 30e-6

f(x) = a*x+b
fit f(x) 'galvanometer.txt' using 2:($1*C) via a,b

plot [0:] 'galvanometer.txt' using 2:($1*C) title "Ausschlag", \
          f(x) title "Ausgleichsgerade"