Fourth Order

In Fresnel's biprism experiment, the source contains two wavelength 6000 Å and 5000 Å. The fourth order bright fringe of first wavelength is at a distance of 3 mm from the central band. The distance of the same order of bright band of second wavelength from the central band is

In a double-slit experiment, two parallel slits are illuminated first bylight of wavelength 400 nm and then by light of unknown wavelength. The fourth-order dark fringe resulting from the known wavelength of light falls in the same place on the screen as the second-order bright fringe from the unknown wavelength. The value of unknown wavelength of light is

Fourth power of (-2) is ____.

Fourth ventricle of brain occurs in

Fourth term of (a+b)^n is

Q Fourth term of (a+b)n is