Final answer:
The number of lines per centimeter in a diffraction grating is determined by dividing the total number of lines by the length of the grating.
Step-by-step explanation:
The number of lines per centimeter in a diffraction grating can be calculated by dividing the total number of lines by the length of the grating.
For example, if a diffraction grating has 10,000 lines in total and the length of the grating is 1 centimeter, then the number of lines per centimeter would be 10,000.
Therefore, the correct answer is Option 1) 10,000.