A Level Physics Practice Exam 2026 - Free A Level Physics Practice Questions and Study Guide

Monochromatic light refers specifically to light that has a single wavelength. This characteristic means that all the light waves are of the same frequency and thus the same color; for example, light from a laser is often monochromatic. The properties of monochromatic light make it particularly useful in various scientific applications, such as in spectroscopy, lasers, and other optical experiments, where precise wavelength and color control is critical.

In contrast, lights with varying wavelengths would contain multiple colors or a spectrum, which does not align with the definition of monochromatic light. Similarly, while light of the same color might suggest uniformity, it does not guarantee that the light has the same wavelength. Light emitted in multiple directions refers to the spread of light, not its spectral composition, which is also unrelated to the concept of monochromatic light. Thus, the most accurate definition involves the light being of the same wavelength.