$A$ mixture of yellow light of wavelength $580 \ nm$ and blue light of wavelength $450 \ nm$ is incident normally on an air film of thickness $2.9 \times 10^{-4} \ mm$. The colour of reflected light is

In a biprism experiment,monochromatic light of wavelength $\lambda$ is used. The distance between the two coherent sources $d$ is kept constant. If the distance between the slit and the eyepiece $D$ is varied as $D_1, D_2, D_3, D_4$ and the corresponding measured fringe widths are $W_1, W_2, W_3, W_4$,then:

When exposed to sunlight,thin films of oil on water often exhibit brilliant colours due to the phenomenon of

An oil film flowing on water appears coloured due to interference. For observing this effect,the approximate thickness of the oil film should be:

In a Fresnel biprism experiment,the eyepiece is placed at a distance of $120 \, cm$ from the source. The distance between the two virtual images is found to be $0.075 \, cm$. If the eyepiece is moved by $1.92 \, cm$ to cross $20$ fringes in the field of view,what is the wavelength of light in $\mathop A\limits^o$?

In a biprism experiment,monochromatic light of wavelength $\lambda$ is used. The distance between two coherent sources is kept constant. If the distance between the slit and the eyepiece $(D)$ is varied as $D_{1}, D_{2}, D_{3}$ and $D_{4}$,and the corresponding measured fringe widths are $z_{1}, z_{2}, z_{3}$ and $z_{4}$,then: