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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?

1

This is a mercury thermometer.

Notice the mercury is at the bottom of the thermometer.

2

When the temperature rises...

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

3

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.

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

1

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.

2

The liquid also needs to expand significantly...

so a small scale can be used to improve precision.

3

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

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