Angular width of the central maxima in the Fraunhoffer diffraction for =6000 Å is ₀ . When the same slit is illuminated by another monochromatic light, the angular width decreases by 30 % . The wavelength of this light is

Step-by-step solution

The angular width of central maxima is given by 2 = 2 a where, = wavelength of light used a = width of the slit For ₁=6000 Å, 2 = ₀ (given) For another light of wavelength ₂ (says), the angular wid th decreases by 30 % so, 2 = ( 100-30 100 ) ₀= 70 100 ₀=0.7 ₀ As slit width is constant, so using Eq. (i) for these values, we get gathered ₀ 0.7 ₀ = ₁ ₂ ₂= ₁ 0.7=6000 0.7=4200 Å gathered