Sodium ion flows a through a cylindrical ion channel --> diameter = 0.85 um and is 5 um long. potential difference b/w the ends of the channel is 225 mV drift velocity = 0.015 m/s in a period of 1 ms, a total of 15*10^6 ions exit the channel a. total charge exiting the channel in 1 ms =? b. current in the ion channel=? i have been trying to find b.) but I think my values might be wrong... PLEASE HELP ME! 2. Relevant equations Q=qnV I=qnAv=Q/change in time change in time = length/drift velocity n=N/V so for a. using the formula for Q: q=1.6*10^-19 N=15*10^6 V=l*PIr^2= (5 um)(PI)(4.25*10^-7)^2=2.8*10^-18 plugging in this value to the equation of Q, I get: Q=2.4*10^-12 (acc to the solutions on the book, this is right) Now, my problem is b.... in this part, I used I=Q/t i know t = length/velocity so i plug in giving me =(5 um)(0.015 m/s) so now that i have t, i just use the Q from a to solve for I and I get 7.2*10^-9. however, according to the solutions this is wrong. it is suppose to be 2.4*10^-9... I have a feeling my Q value for this question is wrong since it's asking for the current IN the ion channel and the Q-value i have is the total charge exiting the channel... so how do I find the Q IN the ion channel?? please help me..!!