electromagnetic waves travel at
c=3*10^8m/s
c=v=wavelength*frequency
Also: c=E/B so B=E/c
So to find the frequency we take;
c/wavelength=frequency
frequency=(3*10^8m/s)/(435*10^-9m)=6.9*10^14Hz
Now to find the Magnetic Field Amplitude we take;
B=E/c
B=(2.70*10^-3V/m)/(3*10^8m/s)=9*10^-12Tesla
Hope this helps. Any questions please just ask. Thank you