228 88Ra ^{228}_{\ 88}{\rm Ra} then decays through a series of beta-minus decays; eventually, another isotope of thorium,

228 90Th ^{228}_{\ 90}{\rm Th} , is formed. How many beta-minus decays will occur during this chain process?

Consider each of the electric- and magnetic-field orientations given next. in each case, what is the direction of propagation of the wave? a)\vec ein the +xdirection,\vec bin the +ydirection. choose+ x direction- x direction+ y direction- y direction+ z direction- z direction b)\vec ein the -y direction,\vec bin the +x choose+ x direction- x direction+ y direction- y direction+ z direction- z direction c)\vec ein the +z direction,\vec bin the -x direction. choose+ x direction- x direction+ y direction- y direction+ z direction- z direction d)\vec ein the +y direction,\vec bin the -z direction. choose+ x direction- x direction+ y direction- y direction+ z direction- z direction