Answer
3.15 V/m
Work Step by Step
Use equation 22–2.
$$c=\frac{E}{B}$$
Here, E and B are the magnitudes of the electric and magnetic fields at the same point in space. Both fields reach their maximum at the same place.
$$E=Bc=(10.5\times10^{-9}T)(3.00\times10^8m/s)=3.15V/m$$