State Moseley.s law.

Explanation

**Step-by-Step Text Solution:**

1. **Introduction to Moseley's Law**: Moseley's law is a fundamental principle in the field of atomic physics that relates the frequency of X-rays emitted by elements to their atomic numbers.

2. **Statement of Moseley's Law**: The law states that the square root of the frequency (ν) of X-rays emitted by an element is directly proportional to the atomic number (Z) of that element.

3. **Mathematical Representation**: This relationship can be expressed mathematically as:
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