P$\mathrm{.}8-5$

The instantaneous expression for the magnetic field intensity of a uniform plane wave

propagating in the $+$y direction in air is given by:

$=4$x$106$ co$[100$y $+$

$4]($A$/$m$)$

a$)$ Determine k$0$ and the location where Hz vanishes at t $=3($ms$)$

b$)$ Write the instantaneous expression for E