Three immiscible transparent liquids with uniform refractive indices $\frac{3}{2}, \frac{4}{3}$ and $\frac{6}{5}$ are arranged one on top of another. The depths of the liquids are 3 cm 4 cm and 6 cm respectively. The apparent depth of the vessel is

When a hydrogen atom is raised from the ground state to the excited state

In the logic circuit diagram, when all the four inputs $\mathrm{A}, \mathrm{B}, \mathrm{C}, \mathrm{D}$ are one, the outputs $\mathrm{Y}_1, \mathrm{Y}_2, \mathrm{Y}_3$ are respectively $(1,1,0)$. When all the inputs $\mathrm{A}, \mathrm{B}, \mathrm{C}, \mathrm{D}$ are changed to 'zero', the outputs $\mathrm{Y}_1, \mathrm{Y}_2, \mathrm{Y}_3$ respectively change to

Two coils have a mutual inductance $5 \times 10^{-3} \mathrm{H}$. The current changes in the first coil according to the equation $I_1=I_0 \sin \omega t$ where $I_0=10 \mathrm{~A}$ and $\omega=100 \pi \mathrm{rad} / \mathrm{s}$. What is the value of the maximum e.m.f. in the coil?