clear
//
//
//

//Variable declaration
d=2                   //diffraction observed(m)
lamda=500*10**-9      //wavelength(m)
x=5*10**-3            //width of central maxima(m)

//Calculation
a=d*lamda/x           //slit width(m)

//Result
printf("\n slit width is %0.3f  mm",a*10**3)