The number of waves in a 3 - cm- thick layer of a liquid is same as in 4 - cm - thick layer of another liquid. If the refractive index of the first liquid is 1.8, then what will be for that of another liquid?

Explanation

To solve the problem, we need to find the refractive index of the second liquid given that the number of waves in a 3 cm thick layer of the first liquid is equal to the number of waves in a 4 cm thick layer of the second liquid. The refractive index of the first liquid is given as 1.8.

### Step-by-Step Solution:

1. **Understanding the relationship between thickness, wavelength, and number of waves:**
The number of waves in a medium can be expressed as:
\[
n = \frac{T}{\lambda}
...