A cell memberane is selectively permeable: some ions can flow through it, and others cannot. When ions diffuse across the membrane, the difference in concentration creates an electric potential difference and an electric field. The difference in concentration of potassium ions inside and outside of the cell is the main contribution to the "resting potential" of a neuron. The Nernst potential is the potential difference across a cell membrane due to the diffusion of ions through it: kgT In AV = Ze Co kg = 1.38 x 10-23 J/K is Boltzmann's constant, T is the temperature in degrees kelvin (K), e is the proton charge, Z is the ionic charge, e is the molar concentration inside the membrane, and c, is the molar concentration outside the membrane. For a singly ionized molecule – like sodium (Na*) or potassium (K+) ions – we have Z = 1. (a) Suppose that the extracellular fluid of a cell – the fluid outside the cell memberane – has a potassium ion con- centration of 0.0045 mol/L and the intracellular fluid – the fluid inside the cell membrane – has a potassium ion concentration of 0.138 mol/L. How much work is required to transport a sodium ion across the membrane, from the outside of the cell to the inside, if the temperature is 37°C? (Ignore the effects of any other ions.) Every neuron has trillions of molecular machines called sodium-potassium pumps embedded in their membranes that use ATP as fuel to do this work. (b) A typical cell membrane has a thickness of about 4 nm. Estimate the electric field (magnitude and direction) inside of the cell membrane. Include a picture that indicates the inside of the cell, the outside, the concentration of ions, and the direction of the electric field.

An uncharged capacitor is connected to the terminals of a 4.0 V battery, and 12 μC flows to the positive plate. The 4.0 V battery is then disconnected and replaced with a 6.0 V battery, with the positive and negative terminals connected in the same manner as before. How much additional charge flows to the positive plate? I tried 05 but that wasnt the answer

The figure below is a graph of an electric potential as a function of position. A function is plotted on a coordinate plane with horizontal axis x and vertical axis V. Points A and B lie on the +x-axis, where A is closer to the origin. The function starts in quadrant 3, curves up and right to reach a local maximum at the origin, then curves down and right to reach a local minimum in quadrant 4. It then curves up and right, crosses the x-axis to the left of point A, and reaches its maximum value directly above point B. The function then curves down and right, crosses the x-axis, and continues until it exits the viewing window in quadrant 4. If a positively-charged particle is released from rest at point A, what will be its subsequent motion?The positively-charged particle will... oscillate around point B. remain at point A.   move to the right. move to the left.

The voltage across a membrane forming a cell wall is 78.7 mV and the membrane is 8.52 nm thick. What is the electric field strength? (The value is surprisingly large, but correct.) You may assume a uniform E-field. (V/m)

An iPhone battery stores 6.55 Wh of energy. How many iPhones could be charged in one day by a small solar panel of dimensions 0.54 m X 0.35 m. Assume that this panel has an efficiency of 18% and is in Gainesville where we get 5.47 kWh/m²/day. Roundoff the number to zero decimals.

Nerve cells in your body can be electrically stimulated; a large enough change in a membrane potential triggers a nerve impulse. Certain plants work the same way. A touch to mimosa pudica, the “sensitive plant,” causes the leaflets to fold inward and droop. We can trigger this response electrically as well. In one experiment, investigators placed electrodes on the thick tissue at the base of a leaf. The electrodes were 3.5 mm apart. When the electrodes were connected to a 47 μF capacitor charged to 1.5 V, this stimulated a response from the plant.a. Eventually, all the charge on the capacitor was transferred to the plant. How much charge was transferred?b. What was the approximate electric field between the electrodes?

Will A or B have a greater change in kinetic energy or will they be equal?

An amount of charge at an electric potential of 25 volts has 150 Joules of electric potential energy. How much charge is at this electric potential?

A 9.0-nm-thick cell membrane undergoes an action potential that follows the curve in the table given. What is the strength of the electric field inside the membrane just before the action potential and at the peak of the depolarization?

A potential difference of 98 mV exists between the inner and outer surfaces of a cell membrane. The inner surface is negative relative to the outer surface. How much work is required to eject a positive sodium ion (Na+) from the interior of the cell? J