•• Figure 1 shows an electric field line from a charge q that was kicked abruptly from res...

•• Figure 1 shows an electric field line from a charge q that was kicked abruptly from rest and has moved a distance d. The kink in the field line occurs between r and r + Δr, where r ≈ ct and t is the time since q was kicked. The radiation from q is carried by the transverse component of ℰ, shown as ℰtr in the picture. Prove that as a function of θ,ℰtr is proportional to sin θ. (This means that the maximum radiation is at θ = 90° and there is no radiation at θ = 0. For this reason, broadcasting antennas are oriented at 90° to the direction in which they need to transmit.)

FIGURE 1