In an LCR series circuit, the potential difference across the terminals of the inductor, capacitor and resistor is 60 V, 30 V and 40 V respectively. Then supply voltage will be equal to

Refractive index of a glass convex lens is $1.5$. The radius of curvature of each of the two surfaces of the lens is 40 cm. The ratio of the power of the lens when immersed in a liquid of refractive index $1.25$ to that when placed in air is

In a biprism experiment, fifth dark fringe is obtained at a point. A thin transparent film of refractive index '$\mu$' is placed in one of the interfering paths. Now $7^{th}$ bright fringe is obtained at the same point. If '$\lambda$' is the wavelength of light used, the thickness of film is equal to

A plane wavefront of width $x$, is incident on an air-water interface and the corresponding refracted wavefront has a width y as shown in figure. The refreactive index of air with respect to water in terms of distances w and z is