binâb-e râye-ye naxost
Fr.: spectre du premier ordre
An optical spectrum, produced by a diffraction grating, in which the difference in path length of light from adjacent slits is one wavelength.
Kepler's first law
qânun-e naxost-e Kepler (#)
Fr.: première loi de Kepler
Planets move in elliptical paths, with the Sun at one focus of the ellipse.
Newton's first law of motion
naxostin qânun-e Newtoni-ye jonbeš (#)
Fr.: première loi newtonienne de mouvement
A body continues in its state of constant velocity (which may be zero) unless it is acted upon by an external force.