question_answer

                A magician during a show makes a glass lens \[\mu =1.5\]disappear in a trough of liquid. What is the refractive index of the liquid? Is the liquid water?                

Answer:

\[\frac{1}{f}={{(}^{1}}{{\mu }_{2}}-1)\left( \frac{1}{{{R}_{1}}}-\frac{1}{{{R}_{2}}} \right)\]                               \[\left[ {{\because }^{1}}{{\mu }_{2}}=\frac{{{\mu }_{2}}}{{{\mu }_{1}}} \right]\] If \[{{\mu }_{1}}={{\mu }_{2}},\] the refractive index of the lens and the surrounding medium is the same: \[\frac{1}{f}=0\] or \[f=\infty \] The lens in the liquid will act like a plane sheet of glass. No, the liquid is not water.