A 60-W Light Bulb Emits Spherical Electromagnetic Waves Uniformly in All

Multiple Choice

A 60-W light bulb emits spherical electromagnetic waves uniformly in all directions.If 50% of the power input to such a light bulb is emitted as electromagnetic radiation,what is the maximum value of the magnetic field at a distance of 2.0 m from the light bulb?

A) 71 nT
B) 0.35 $\mu$ T
C) 0.14 $\mu$ T
D) 0.20 $\mu$ T
E) 0.10 $\mu$ T