first-order spectrum 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 (year 1609). |
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. |