Light is one of the necessary conditions for biological growth and development.

Heat:

Heat refers to when the change of system state comes from the destruction of thermal balance conditions.

Difference:

1, different definitions

24 hours a day is a light cycle in nature. When there is light, it is a bright period, and when there is no light, it is a dark period.

Due to the thermal interaction between the system and the outside world, energy is transferred from a high-temperature object to a low-temperature object, and the transferred energy is called heat.

2, the unit is different

The brightness of the light emitted by the light source is the luminous intensity, that is, the light energy of the light source, and the unit is candlelight.

In nutrition, "kilocalorie" is used as a unit of heat. 1 kcal is the heat required for 1L water to rise from 15℃ to 1℃.

3, the principle is different

Illuminance is the degree to which an object is illuminated, that is, the ratio of the luminous flux obtained on the surface of the object to the illuminated area. The unit is Ix(l lux is the illuminance generated by uniform illumination of L square meters with luminous flux of L lumens) or foot candle (1 foot candle is 1 illuminance generated by uniform illumination of luminous flux of lumens 1 square foot area), 1 foot candle = 65438. Illuminator for measuring light intensity.

The relationship between heat energy and internal energy is just like the relationship between work and mechanical energy. Heat is a measure of the change of energy inside an object. If the thermal balance between the two areas has not been reached, the heat will be transferred to the other side with low temperature at the place with high temperature between them.

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