The distance between the 1st and 2nd maxima is 0.3 cm when the screen is located 2 m away. if d = 0.4 mm, a) what is the wavelength?
b) what is the size of central peak?

a) The wavelength of light is 6×10^-7 m.

b) The size of the central peak is 6×10^-3 m.

Explanation:

let:

α be the distance between the 1st and 2nd maxima

d = 0.4 mm be the grating slit space

X be the distance to the screen

a) α = λ×X/d

   λ = α×d/X

      = (0.3×10^-2)×(0.4×10^-3)/(2)

      = 6×10^-7 m

Therefore, the wavelength of light is 6×10^-7 m.

b) the size of the central peak is given by:

 D = 2×λ×X/d

     = 2×(6×10^-7)×(2)/(0.4×10^-3)

     = 6×10^-3 m

Therefore, the size of the central peak is 6×10^-3 m.

what experimental evidence led scientists to change from the previous model to this one?

a few of the positive particles aimed at a gold foil seemed to bounce back.

the colors of light emitted from heated atoms had very specific energies.

experiments with water vapor showed that elements combine in specific proportions.

cathode rays were bent in the same way whenever a magnet was brought near them.