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Mercury Thermometers, Sensitivity, Linearity and Range

Mercury Thermometers, Sensitivity, Linearity and Range

Mercury Thermometers, Sensitivity, Linearity and Range

What is a mercury thermometer and what are its properties, such as sensitivity, linearity and range.

Mercury is a metal and it is...

What happens to liquid when it warms up?

Which of the following is the best description of a mercury thermometer?

Imagine a thin, glass tube with mercury in it. When temperatures rise, the mercury will expand. Does that mean it will move further up or further down the tube?


This is a mercury thermometer.

Notice the mercury is at the bottom of the thermometer.


When the temperature rises...

...the mercury expands and moves up the tube.


We can read off the temperature...

...on the scale on the side of the thermometer.

Can we use any liquid in a thermometer?

Which properties must the liquid used inside a thermometer have? Select all the option you think are correct.

You can select multiple answers

Why does the liquid used in a thermometer need to expand linearly with temperature?

Why does the liquid need to expand significantly with a temperature increase?

The smaller the scale the more precisely we can measure the temperature. If you couldn't really tell the difference in volume of the mercury if it was 6 degrees or 7 degrees, but you could only tell the difference if it was 5 degrees or 10 degrees, you might have to have 5 degrees steps on the scale. So it would be hard to see exactly if the temperature was 6 degrees of 7 degrees, for example.

Why is it important the liquid has a low freezing point and high boiling point?

To sum up


The liquid used in a thermometer needs to expand linearly with temperature change...

so that when the temperature increases by a set amount, the liquid also expands by a set amount. This means that we can use a scale to measure the temperature change.


The liquid also needs to expand significantly...

so a small scale can be used to improve precision.


Finally, it has to have a high boiling point and low melting point...

so that the thermometer will still work in more extreme temperatures.