Science — CBSE Class 10 board question

(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:

$$_{d}n_{w} = \frac{n_w}{n_d} = \frac{1.33}{2.42} \approx 0.55$$

• (a) Since diamond is optically denser than water, the ray bends away from normal on entering water. Label: incident ray, normal, refracted ray, diamond, water, interface.
• (b) Refractive index of medium 2 w.r.t. medium 1 = (absolute RI of medium 2) ÷ (absolute RI of medium 1). Here diamond is medium 1, water is medium 2. The value < 1 confirms water is rarer than diamond.