(a) Ray diagram — light goes from diamond (denser) to water (less dense), bending away from the normal:
```
Diamond | Water
|
\ | /
\ | /
\ N /
\ | /
\ | /
-------\|/------- interface
*-------- refracted ray (bends away from normal)
|
N'
```
(Incident ray in diamond, normal at point of incidence, refracted ray in water bending away from normal — label all three)
---
(b) Refractive index of water w.r.t. diamond:
$$_{d}n_{w} = \frac{n_w}{n_d} = \frac{1.33}{2.42} \approx 0.55$$