The magnetic field amplitude of an electromagnetic wave is 2 × 10^-7 T. Its electric field amplitude, if the wave is travelling in free space is:

60 V/m

Speed of light, c = $\frac{E_0}{B_0} \Rightarrow E_0=B_0 c$

Given, $B_0=2 \times 10^{-7} \mathrm{~T}, c=3 \times 10^8$ m/s

∴ $E_0=2 \times 10^{-7} \times 3 \times 10^8$ = 60 T m/s = 60 V/m