Radius of dark Newton’s ring formula

Newton’s rings are annular interference maxima and minima that appear around the point of contact between a convex lens and a plane—parallel plate when light passes through the lens and plate. When the difference in the path of the beam reflected from the convex surface of the lens at the glass-air boundary and the beam reflected from the plate at the air-glass boundary is equal to an entire wave, then these two waves hit the observation point with the same faces and demonstrate interference.

Links:

  1. Wikipedia (ru), last formula in paragraph.

radius

radius of the dark Newton’s ring.

Symbol:

r

Latex:

\(r\)

Dimension:

length

wavelength

wavelength.

Symbol:

lambda

Latex:

\(\lambda\)

Dimension:

length

ring_order

Ring’s order. See positive_number.

Symbol:

N

Latex:

\(N\)

Dimension:

dimensionless

lens_radius_of_curvature

Lens radius_of_curvature.

Symbol:

R

Latex:

\(R\)

Dimension:

length

medium_refractive_index

relative_refractive_index of the medium between the lens and the plate.

Symbol:

n

Latex:

\(n\)

Dimension:

dimensionless

law

r = sqrt(N * R * lambda / n)

Latex:
\[r = \sqrt{\frac{N R \lambda}{n}}\]