The upstream of a river can be determined by

a the direction of the mouths of the v shapes on contour lines

b which way is south from the map's compass

c examining the highest elevation on the map

d the direction of the points of the v shapes on contour lines

An electromagnetic wave with frequency 65.0 hz travels in aninsulating magnetic material that has dielectric constant 3.64 andrelative permeability 5.18 at this frequency. the electric fieldhas amplitude 7.20 \times 10^{ - 3} {\rm v}/{\rm m}. a. what is the speed of propagation of the wave? b.what is the wavelength of the wave? c.what is the amplitude of the magnetic field? d.what is the intensity of the wave?