Chapter 8 - Temperature
*State the thermometric property that defines the temperature scale in a liquid-in-glass thermometer.
Volume of a fixed mass of liquid.
*Describe how you would calibrate an unmarked mercury-in-glass thermometer.
Place the bulb of the unmarked thermometer in pure melting ice at a pressure of 1 atmosphere.
When the mercury level is steady, mark this position as 00C.
Next, place the bulb of the unmarked thermometer in steam above boiling water at pressure of 1 atmosphere.
When the mercury level is steady, mark this position as 1000C.
Divide the interval between 00C and 1000C into 100 divisions.
Each division represents 10C.
*Explain what it meant by responsiveness of the thermometer.
A responsive thermometer reacts quickly to changes in temperature.
*Explain what is meant by sensitivity of the thermometer.
A sensitive thermometer gives a more noticeable expansion (large increase in the length of the mercury thread) for small changes in temperature.
*State the set up of a thermocouple and describe how works.
A thermocouple consists of two types of wires made of different metals.
The ends of the wires are joined to form two junctions.
When the two junctions are at different temperature (one hot and one cold), a small voltage (e.m.f) is produced.
The greater the difference, the greater the voltage produced across the two junctions. That is, the voltage produced is proportional to the temperature difference.
By knowing one reference temperature and measuring the voltage, the unknown temperature can be found.