A square loop of wire in the x-y plane is centered at the origin with its edges (each of length 2a) parallel to the axes. Current flows counterclockwise around the loop as viewed from the positive z-axis. The time-dependence of the current is

where τ > 2a/c.
(a) Show that the radiation vector α(r, t) = ŷ α(r, θ, t) when r = r cos θ ẑ + r sin θ x̂.
(b) Compute α(t) and make a careful graph of this function for fixed r and θ.

Transcribed Image Text:

I(t) = 0 lot/t Io t < 0, 0