1 Many people find that boxes with a 1.25 or 1 1/8 hole restrictor on them before an egg is laid are not utilized, even by smaller birds like titmice and chickadees. 2  If the entrance hole is enlarged (e.g., by woodpeckers or chewing rodents), put a hole reducer on it.
The Doppler effect widens the spectral lines of rotating objects because the wavelengths changes from blue or red. Blue-shifted, red-shifted, and non-shifted photons mix together to get how its rotating.
The Stark effect is the shifting and splitting of spectral lines of atoms and molecules due to presence of an external electric field. The amount of splitting or shifting is called the Stark splitting or Stark shift. In general, one distinguishes first- and second-order Stark effects. The first-order effect is linear in the applied electric field, while the second-order effect is quadratic in the field. The Stark effect is responsible for the pressure broadening of spectral lines by charged part