Which of the following is the unit of intensity?

• A. W/cm2 (Watts per cm squared)
• B. mW
• C. Pascal
• D. dB/cm (decibels per cm)

Answer: (A)

The unit of intensity is defined as power per unit area. In the context of sound and other wave phenomena, intensity quantifies how much energy is transmitted through a specific area over time. The correct option, Watts per cm squared, effectively represents this definition.

Intensity is mathematically expressed as:

[ I = \frac{P}{A} ]

where ( I ) is the intensity, ( P ) is the power in watts, and ( A ) is the area in square centimeters. Therefore, using the unit of Watts (W) for power and cm² for area gives the unit of intensity as W/cm².

While the other options may represent various measurements, they do not accurately describe intensity in a manner consistent with the definition. For instance, mW measures power but does not incorporate the area element necessary for intensity. Pascal is a unit of pressure, and dB/cm is often used in contexts such as sound intensity levels, but it involves a logarithmic scale rather than a direct measurement of intensity as defined.