In a diffraction pattern due to a single slit of width a , the first minimum is observed at an angle 300when light of wavelength 5000Å is incident on the slit. The first secondary maximum is observed at an angle of

For first minimum, the path difference between extreme waves, asinθ=λ Here θ=30°⇒sinθ=12  ∴a=2λ..........(1)For first secondary maximum, the path difference between extreme wavesasinθ'=32λ or   (2λ)sinθ'=32λ [Using eqn (i)]  or sinθ'=34  ∴  θ'=sin-134