Ascreen is placed 50cm from a single slit illuminated with 690nm light. if the distance between the first and third dark fringes in the diffraction pattern is 3mm.
a) find the width of the slit
used w=(2\lambdal)/d to get 500 mm
b) find the width of the central bright fringe using w=(2\lambdal)/d .

Explanation:

a ) Distance of screen (D) = 50 X 10⁻²

Wavelength of light λ = 690 x 10⁻⁹

d  = width of slit

Distance between first and third dark fringe = 2 x fringe width

= 2 x λD/d = 3 x 10⁻³

d = 2 x 690 x 10⁻⁹ x 50 x 10⁻² /3 x 10⁻³ =  0.23 mm

b ) Width of central bright fringe = 2 λD/d

2 x 690 x 10⁻⁹ x 50 x 10⁻² /23 x 10⁻⁵ m

= 3 mm.

specific latent heat of fusion, lf, of a substance is defined as the amount of heat required to change a unit mass of the substance from solid to liquid state, without any change in the temperature.

explanation:

i wanna say it’s between b and d, leaning more towards b.