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# Heat capacity or Thermal capacity

heat capacity or thermal capacity is defined as the amount of heat energy required to raise the temperature of a body by 10C. It is denoted by C’.

Heat capacity or Thermal capacity

Now, you are familiar with specific heat capacity. It is the heat required to raise the temperature of a unit mass of the body by 10C. But, heat capacity is the heat required to raise the temperature of a entire mass of the body by 1˚C. Thus, heat capacity or thermal capacity is defined as the amount of heat energy required to raise the temperature of a body by 10C. It is denoted by C’.

Heat Capacity = Quantity of heat required / Rise in temperature

CI  = Q/t

SI unit of heat capacity is J/K. It is also expressed in cal/˚C, kcal/˚C or J/˚C.

As we saw earlier, if C is the heat required to raise the temperature of unit mass of the body by 1˚C then the heat required to raise the temperature of ‘m’ mass of the substance is m C. So, heat capacity is also given as, CI = m x C.

### Exercise 1.5

An iron ball requires 5000 J heat energy to raise its temperature by 20ºC. Calculate the heat capacity of the iron ball.

### Solution:

Given, Q 5000 J, ΔT 20ºC or 20 K

Heat Capacity C = Heat energy required, Q / Rise in temperature, T

= 5000/20

= 250 JK-1

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9th Science : Heat : Heat capacity or Thermal capacity |