Intensity

Intensity is a widely-used term, which can refer to:

In colloquial use:

• Strength
• Amplitude
• Level
• Magnitude

In optics:

• Radiant intensity, power per unit solid angle (W/sr)
• Luminous intensity, luminous flux per unit solid angle (lm/sr or cd)
• Irradiance, power per unit area (W/m²)

Other uses:

• Value intensity in philosophy and ethics
• Exercise intensity, a measure of how much work is done during exercise (% of max heart rate)