Harper suffers from nearsightedness equally severely in both eyes. The focal length of either of Harper's eyes is 16.7 mm in the relaxed state. What lens strength (a. k.a., lens power) of contact lenses should be prescribed to correct the nearsightedness in Harper's eyes

Large electric fields in cell membranes cause ions to move through the cell wall. the field strength in a typical membrane is 1.0 x 10 7 n/c. what is the magnitude of the force on a calcium ion with charge +e? what is its acceleration? is it possible for a particle with the same charge as as calcium to have a different acceleration if placed at this location? what would change the acceleration: mass of the particle? diameter of the particle?