Which label belongs in the area marked x? radiation is x

a. must involve temperature differences between substances or objects

b. only occurs when molecules are in direct contact

c. involves the movement of fluids based on density differences

d. can occur where there is little or no matter

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?