Which of the following correctly gives the refractive index of water with respect to air

PHYSICS · Single correct · AP · Physics 2: Algebra-based · Geometric Optics · Geometric Optics

Problem

Which of the following correctly gives the refractive index of water with respect to air, if

n_{\text{air}}=n_1

and

n_{\text{water}}=n_2

? (a)

\dfrac{n_1}{n_2}

(b)

\dfrac{n_2}{n_1}

(c)

n_2

(d)

n_2-n_1