Adipole array consists of three z-directed dipole elements placed along the y-axis at y=0, d and 2d. the 3 half-wave dipoles are uniformly excited. (a) find the far field e r radiated by the array. identify the element pattern and the array factor in e r . (b) plot the radiation pattern in the xy-plane (|eθ| vs. φ) in polar form for d=λ/2 using the graphical method. (c) repeat for d=3λ/4 and d=1λ. describe what you observe as d is increased.

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?