The unit for wavelength is:

• A. Millimeters
• B. Hertz
• C. Microseconds
• D. Milliliters

Answer: (A)

Wavelength is a measure of the distance between successive peaks (or troughs) of a wave, often represented in physical contexts such as light, sound, and electromagnetic waves. The standard unit for measuring wavelength in the International System of Units (SI) is meters. However, since wavelengths can vary widely, they can also be expressed in smaller units like millimeters, centimeters, or nanometers for convenience in various applications.

In this context, millimeters is an appropriate unit for wavelength, especially when dealing with waves that have longer wavelengths, such as certain radio waves or sound waves. While other options, such as hertz, microseconds, and milliliters, relate to other physical quantities (frequency, time duration, and volume, respectively), they do not serve as units for measuring wavelength. Thus, expressing wavelength in millimeters aligns correctly with its definition and usage in physics.