Physics

Problem

Which of the following correctly relates the relative refractive indices

n_{12}

n_{23}

and

n_{13}

for three successive media 1, 2 and 3? a)

n_{12}+n_{23}=n_{13}

\dfrac{1}{n_{12}}+\dfrac{1}{n_{23}}=\dfrac{1}{n_{13}}

n_{12}n_{23}=n_{13}

\dfrac{n_{12}}{n_{23}}=n_{13}