In SI system, power per area {intensity measurement} can be power per steradian. Informally, intensity is flux per steradian, pressure divided by time, or force per second per unit distance.
Sound intensity uses logarithmic scale {bel}, or its tenths {decibel} (db) (dB), so 10 db equals 1 bel. Whispers are 30 db. Siren loudness is 100 dB. Larger units {neper} are 6.686 db.
Light intensity compares to standard candle {candela, intensity} (cd) {international candle} {candle, light} {lumen, light}. One candela is light intensity 1/683 watts per steradian, at frequency 540 * 10^12 hertz.
Physical Sciences>Physics>Measurement>Kinds>Mass
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Date Modified: 2022.0224