The membrane that surrounds a certain type of living cell has a surface area of 4.50 10-9 m2 and a thickness of 1.08 10-8 m. Assume that the membrane behaves like a parallel plate capacitor and has a dielectric constant of 5.40. If the charge in part (a) is due to K+ ions (charge +e), how many such ions are present on the outer surface?

Question

The membrane that surrounds a certain type of living cell has a surface area of 4.50  10-9 m2 and a thickness of 1.08  10-8 m. Assume that the membrane behaves like a parallel plate capacitor and has a dielectric constant of 5.40. If the charge in part (a) is due to K+ ions (charge +e), how many such ions are present on the outer surface?

drwls · Answer

I would need to know the "charge in part (a)" to answer that. You have not said what it is. If you know the charge, you only have to divide by e to get the number of K+ ions

Julie · Answer

I know the voltage is 54.6*10^-6V but when I tried to determine the charge, I got it wrong

Julie · Answer

(a) The potential on the outer surface of the membrane is +54.6 mV greater than that on the inside surface. How much charge resides on the outer surface?

Elena · Answer

ε₀=8.85 •10⁻¹² F/m ε=5.4 e =1.6•10⁻¹⁹ C A=4.50•10⁻⁹ m² d=1.08•10 ⁻⁸ m U=54.6•10⁻³V C=ε•ε₀•A/d C=q/U ε•ε₀•A/d =q/U q= ε•ε₀vA•U/d q=Ne N=q/e