# The amplitude of the magnetic field part of a harmonic electromagnetic wave in vacuum is $B_o = 510\: nT$. What is the amplitude o the electric field part of the wave?

$\begin {array} {1 1} (a)\;153 N/C & \quad (b)\;15.3 N/C \\ (c)\;0.153 N/C & \quad (d)\;1.53 N/C \end {array}$

Amplitude of magnetic field, $B_o = 510\: nT = 510 \times 10^{-9}T$
$E = cB_o = 3 \times 10^8 \times 510 \times 10^{-9} = 153 N/C$
Ans : (a)