Name the electromagnetic waves used for studying crystal structure of solids. What is its frequency range?

Explanation

**Step-by-Step Solution:**

1. **Identify the Electromagnetic Waves Used**: The electromagnetic waves used for studying the crystal structure of solids are X-rays.

2. **Explain the Relevance of X-rays**: X-rays are particularly useful in crystallography because they have wavelengths that are comparable to the distances between atoms in a crystal lattice. This allows for effective diffraction patterns to be obtained, which can be analyzed to determine the structure of the crystal.

3. **Mention Bragg's Law**: The method commonly used to study crystal structures with X-rays is based on Bragg's Law, which is expressed as:
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