Under certain circumstances, potassium ions (K*) move across the 8.0-nm-thick ce

Question

Under certain circumstances, potassium ions (K*) move across the 8.0-nm-thick cell membrane from the inside to the outside. The potential inside the cell is -70 mV and the potential outside is zero. (a) What is the change in the electrical potential energy of the potassium ions as they move across the membrane? 1.12e-17X Does their potential energy increase or decrease as they move from the inside to the outside? O increase decrease (b) What electrical force (magnitude and direction) is exerted on the potassium ions when they are inside the potassium channel that spans the cell membrane, assuming that it behaves electrically like water? magnitude direction Select

Explanation / Answer

potential difference = vf - vi = 0-(-70) = 70 x 10^-3 v

a) change in potential energy = ( vf - vi) * q = 70 x10^-3 * 1.6x10^-19 = 1.12 x10^-20 joules

b) electric force F = -du/ dy

                         = - 1.12 x10^-20 / 8 x10^-9 = - 1.4 x10^-12 N

magnitude = 1.4 x10^-12 N

direction is opposite to motion that is out side to inside

Related Questions

Navigate

• Browse (All)
• Browse U
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.