physics c/wk...i=kv^n and log numbers!

i'm doing physics c/wk.....and i have to find a characteristic equation for a filament lamp in the form.... I= kV^n

i've plotted a graph of I/V by converting my results into log numbers and found the gradient and y-intercept.......but i don't know what to do from there! :frown:

help please!! :frown:

Reply 1

mc_watson87

Saf!

help please!! :frown:

I'm not quite sure the question... but if you want to confirm the equation I=kV^n
Logging it gives you...
=> logI = logkv^n
=> logI =logk + logv^n
=> logI = logk +nlogv

Compare that with y=mx+c (equation for a straight line)
Y= log I
m= n
x= log v
c= log k

So plotting logI on Y axis and log v on X axis would give you a straight line with y intercept log k and gradient n... if that is shown it confirms the equation I= kV^n... and then you can plug in your values from the graph to get your version of the equation.

(not sure if thats wat ya wanted to know)

Reply 2

Saf!

but do you inverse log the values before putting them in the equation???

Reply 3

mc_watson87

Saf!

but do you inverse log the values before putting them in the equation???

The gradient is n, so you wouldn't need to for that.

The y-intercept is log k, so yea you wud inverse that... 10^logk to get k and then you could put it into the equation.