Imagine marching a line of people from a smooth sidewalk (rarer medium) onto thick mud (denser medium) at an angle; the side that hits the mud first slows down, causing the entire line to pivot and change direction towards the normal.

FAST: Faster to denser, Air to Solid, bends Toward normal.

According to Snell's Law of refraction, the product of the refractive index and the sine of the angle of incidence in one medium is equal to the product for the second medium: $n_1 \sin(i) = n_2 \sin(r)$. Substituting the given values ($n_1 = 1.0$, $n_2 = 1.5$, and $i = 45°$), we find $\sin(r) = \frac{1.0 imes \sin(45°)}{1.5} \approx 0.4714$, which gives $r = \arcsin(0.4714) \approx 28.1°$.

Always verify whether light is traveling from rarer to denser or denser to rarer to determine if the angle of refraction should be smaller or larger than the angle of incidence.