Name: Constant Volume Gas Thermometer
Uploaded: 2019-07-19
Duration: 8 min 7 s
Description: You all have learned to use a mercury thermometer. Now, let us learn an interesting way of measuring temperature with the help of gas in this video.

Question

Discuss about cubical expansion of a liquid. Explain the terms coefficient of real cubical expansion and apparent cubical expansion. Establish relation between them.

Accepted Answer

Cubical expansion of a liquid can be defined as the change in volume of liquid with change in temperature. It is basically the change in the volume of the liquid.

The coefficient of real expansion and the coefficient of apparent expansion of liquid can be defined and established as:

•Coefficient of real expansion is actually defined as the ratio of the real change in the volume to its original volume per 1 degree rise in the temperature.

•Coefficient of apparent expansion of the liquid is actually defined as the ratio of the apparent change in volume of the liquid to the original volume per 1 degree rise in the temperature.

Now, a liquid is heated in the container, then heat flows through the container to liquid. This means that container expands first due to which level of the liquid falls. When liquid gets heated, it will expand more and beyond of its original value. Actually we can't observe the intermediate state. We can only observe initial and the final levels. Observed expansion of the liquid is called the apparent expansion of the liquid and is less than of its actual expansion.

Now on heating, expansion of the liquid will appear to be from $L_{1}$ to $L_{2}$ . This is actually called the apparent expansion of the liquid. But actually the liquid on heating has expanded from $L_{2}$ to $L_{3}$ , this is now called the real expansion of liquid.

Real expansion of liquid is every time greater than apparent expansion of liquid.

Fall in the level of liquid from $L_{1}$ to $L_{2}$ is actually equal to increase in volume of the flask.

Hence, Expansion of liquid = Apparent expansion of liquid + Volume expansion of container.

Discuss about cubical expansion of a liquid. Explain the terms coefficient of real cubical expansion and apparent cubical expansion. Establish relation between them.

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