Question

The resting potential difference from the outside to the inside of an axon is Δ1--84 my (the potential is lower inside the axon). What is the potential energy of a K+ ion located inside the axon if zero potential energy is defined as zero outside the axon? A. F-134 meV B. U-- 84 meV C. U +134 meV D. 는 +84 meV E. 13.6 meV 4. U-qV-e*(-84 mV)--84 mEV (Ans: B)

The answer is already there, I am looking for an explanation.

Answer 1

Here given ion for consideration is K+ ion . The charge on K+ ion is = +ve of charge on electron = +Qe

now energy = charge Qe x potential V = Qe x (-84mV) = -84QemV.

Since Qe also can be written as only 'e' , hence E = -84meV

Unit conversion :- 1eV = 1.6 x 10^-19 joule

hence -84meV = -84 x 1.6 x 10^-19 x 10^-3 joule = -134.4 x 10^-22 joule