In a certain experiment, a radio transmitter emits sinusoidal electromagnetic waves of frequency 115.0 MHzMHz in opposite directions inside a narrow cavity with reflectors at both ends, causing a standing wave pattern to occur. A. How far apart are the nodal planes of the magnetic field? Answer in meters
B. If the standing wave pattern is determined to be in its eighth harmonic, how long is the cavity? Answer in meters

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?