How Strong is the Electric Field Across a Cell Membrane?

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SUMMARY

The electric field across a cell membrane is determined by the potential difference and the membrane's thickness. The potential difference is approximately 0.0730 V, and the membrane thickness is 8.22E-9 m. The user initially attempted to calculate the electric field using incorrect formulas, leading to confusion. The correct approach involves treating the cell membrane as a capacitor, which relates electric field (E), voltage (V), and thickness (d) through the formula E = V/d.

PREREQUISITES
  • Understanding of electric fields and potential difference
  • Familiarity with capacitor theory and equations
  • Basic knowledge of physics formulas involving voltage and distance
  • Proficiency in unit conversions, particularly between volts, coulombs, and joules
NEXT STEPS
  • Study the relationship between electric field, voltage, and distance in capacitors
  • Learn about the physics of cell membranes and their electrical properties
  • Explore the derivation and application of the formula E = V/d
  • Investigate common mistakes in electric field calculations and how to avoid them
USEFUL FOR

Students in physics, biophysicists, and anyone interested in understanding the electrical properties of biological membranes.

Boozehound
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The inner and outer surfaces of a cell membrane carry a negative and positive charge, respectively. Because of these charges, a potential difference of about 0.0730 V exists across the membrane. The thickness of the membrane is 8.22E-9 m. What is the magnitude of the electric field in the membrane?

so i took .0730V and multiplied it by 1.60E-19C to get an answer in joules. i ended up getting 1.168E-20J. i then took that and divided it by .0730V to get an answer in coulombs. and i got 1.6E-19C for that. then i took my answers and plugged them into the equation. E=8.99E9(1.6E-19)/(8.22E-9)^2. then the final answer i got was . and i punched it in and it was wrong. i don't know if i am using the wrong formulas. most likely that's the case. so if you see something I am doing wrong and can point me in the right direction that would be a great help. thanks.
 
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wait, too hard, and I'm thinking youre confused re maybe the notion of a test charge. I think, iirc, you just need to treat this as a ccapacitor which relates E,V, and thickness.
 

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