Question
Write Newton's law of cooling and explain the necessary condition for it and also explain the cooling curve.
✓
Answer
Newton's law of cooling : According to Newton's law of cooling, if the heat excess is less than the surrounding environment, then the net energy emitted per second by the object or rate of cooling of the object is proporitonal to the heat excess. This law was propounded by Newton through experiment.
Necessary conditions : (1) The value temperature difference of the object and the surroundings should be less than the absolute temperature of the surroundings i.e. $\text T_0 = \text {Absolute temperature of surrounding}$
(2) Heat loss from the object should be only through radiation.
(3) This law is obtained from Stefan, Boltzmann law which applies for black-body so the radiating surface should be black.
Cooling curve : The graph between the temperature of the body and time is called cooling curve. The gradient of the tangent at any point on the curve gives the rate of temperature.
Necessary conditions : (1) The value temperature difference of the object and the surroundings should be less than the absolute temperature of the surroundings i.e. $\text T_0 = \text {Absolute temperature of surrounding}$
(2) Heat loss from the object should be only through radiation.
(3) This law is obtained from Stefan, Boltzmann law which applies for black-body so the radiating surface should be black.
Cooling curve : The graph between the temperature of the body and time is called cooling curve. The gradient of the tangent at any point on the curve gives the rate of temperature.
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