The ratio of intensities of consecutive maxima in the diffraction pattern due to a single slit is

I=I0sinαα2,  where  α=φ2For  nth secondary maxima  dsinθ=2n+12λ⇒α=φ2=πλdsinθ=2n+12π∴   I=I0sin2n+12π2n+12π2So  I0:I1:I2=I0:49π2I0:425π2I0=1:49π2:425π2