The colours observed in thin soap bubbles are due to

Dark and colour patterns on thin soap films are due to

Which of the following produces coherent waves?

White light may be considered to be a mixture of waves with $\lambda$ ranging between $3900\ \mathring A$ and $7800\ \mathring A$. An oil film of thickness $10,000\ \mathring A$ is examined normally by reflected light. If $\mu = 1.4$,then the film appears bright for

When a mica sheet of thickness $7 \ \mu m$ and refractive index $\mu = 1.6$ is placed in the path of one of the interfering beams in a biprism experiment, the central fringe shifts to the position of the seventh bright fringe. The wavelength of the light used is $............ \ \mathring{A}$.

In a biprism experiment, the distance of the source from the biprism is $1 \, m$ and the distance of the screen from the biprism is $4 \, m$. The refracting angle of the biprism is $\alpha = 2 \times 10^{-3} \, \text{radians}$. The refractive index $\mu$ of the biprism is $1.5$ and the wavelength of light used is $\lambda = 6000 \, \mathring{A}$. How many fringes will be seen on the screen?