What is the equation for intensity?

What is the equation for intensity?

• A. Intensity (W/cm2) = Power (W) / Area (cm2)
• B. Intensity (W/cm2) = Power (W) * Area (cm2)
• C. Intensity (W/cm2) = Power (W) - Area (cm2)
• D. Intensity (W/cm2) = Power (W) / Area (cm2)

Answer: (D)

Intensity is the rate at which energy passes through a given area. That means you take the total power and spread it over the area it covers, so the correct relationship is power divided by area. The units come out as watts per square centimeter (W/cm^2) when area is in cm^2, exactly matching the given unit. If you kept the same power but increased the area, the intensity would decrease because the energy is spread over a larger surface. Conversely, concentrating the same power over a smaller area increases intensity. Multiplying by area or subtracting area wouldn’t describe energy flow per unit area, so division is the appropriate form.

Intensity is the rate at which energy passes through a given area. That means you take the total power and spread it over the area it covers, so the correct relationship is power divided by area. The units come out as watts per square centimeter (W/cm^2) when area is in cm^2, exactly matching the given unit. If you kept the same power but increased the area, the intensity would decrease because the energy is spread over a larger surface. Conversely, concentrating the same power over a smaller area increases intensity. Multiplying by area or subtracting area wouldn’t describe energy flow per unit area, so division is the appropriate form.