Temperature Notes | Study Mechanical Engineering SSC JE (Technical) - Mechanical Engineering

TEMPERATURE

Zeroth law of Thermodyamics
• The zeroth law of thermodynamics states that if two thermodynamic systems are each in thermal equilibrium with a third one, then they are in thermal equilibrium with each other.
• Zeroth law of thermodynamics is the basis of temperature measurement

• Thermocouple uses copper–constantan, platinum, rhodium, thodium, chromel alumel combinations.

Temperature

The temperature is a measure(degree) of hotness or coldness.(freezing cold, warm hot)

Temperature scales

• They are related to absolute temperature scales.
• The temperature scales used in the SI and English system are the celsius scale and the Fahrenheit scale, respectively.
• A scale of temperature independent of the thermometric substance is called a thermodynamic temperature scale.
• Kelvin scale is related to celsius scale by

                              T(K) = T(C) + 273.16

• Rankine scale is related to Fahrenheit scale by

                              T(K) = T(C) = 459.67

• The temperature scales in the two unit systems are related by

                              T(R) = 1.8T(K)

                              T(⁰F) = 1.8T(⁰C) + 32

                              ΔT(⁰F) = 1.8ΔT(K) = ΔT(R)