1.18. A dielectric slab of polystyrene ( 2.5680,=) of height 2h is bounded a) above and below by free space, as shown in Figure P1-18. Assuming the electric field within the slab is given by 8 (a,5+10) cos(at - Bx) where Bos, determine the: (a) Corresponding magnetic field within the slab. (b) Electric and magnetic fields in free space right above and below the slab. Ephe h 2.56 2.56 fo X бо но Figure P1-18