What is the name given to light that has a single wavelength?

• A. Polychromatic light
• B. Monochromatic light
• C. White light
• D. Filtered light

Answer: (B)

Light that has a single wavelength is termed monochromatic light. This type of light consists of one specific color or frequency, which means it does not contain multiple wavelengths or colors like polychromatic light does. Monochromatic light is often produced by lasers, which generate highly coherent light at a specific wavelength, or by using a monochromator that filters out all wavelengths except for a designated one.

In contrast, polychromatic light includes a range of wavelengths, such as white light, which contains all the colors of the visible spectrum. Filtered light can refer to light that has had certain wavelengths removed, but it does not specifically denote a single wavelength. Therefore, the clarity and specificity inherent in the definition of monochromatic light make it the correct answer to this question, emphasizing the importance of wavelength in understanding the properties of light.