The product of the peak value of the magnetic field and the velocity of light is the peak value of electric field strength. Thus, the value of peak electric field strength is obtained by inserting the value of magnetic field and the velocity of light. As a result, the amplitude of the electric field in an EM wave is proportional to the magnitude of the magnetic field.
By applying the equation we get,
E0=cB0
where, E0 is the electric field
B0 is the magnetic field
c is the velocity of light.
Substituting the values in the above equation,
E0 = 3 × 108 × 20 × 10−9
=6V/m