Answer: [tex]\Delta U=[/tex] 1.922x10⁻²⁰ Joules
Explanation: Electric Potential Energy (U) is the energy a charged object has due to its location in an electric field and it will only exist with the object is charged.
Voltage or Electric Potential Difference (V) is external work done to move a charge from one point to another in a electric field.
These terms have a relationship, which is given by:
[tex]\Delta U=q\Delta V[/tex]
where
q is the charge
Proton is positive and has a charge of 1.6x10⁻¹⁹C.
Unit for potential energy is Joule (J). The relation between mV and J is
1mV = 10⁻³J
Then:
V = 120x10⁻³
V = 0.12
So, for a proton to move from the negative side of a membrane to the positive:
[tex]\Delta U=q\Delta V[/tex]
[tex]\Delta U=1.6.10^{-19}.0.12[/tex]
[tex]\Delta U[/tex] = 1.922 x 10⁻²⁰
Energy necessary to transport a proton from negative side of the membrane to the positive is 1.922 x 10⁻²⁰J.
