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A thermometer uses a thermometric property to measure temperature - Leaving Cert Physics - Question 12 - 2015
Question 12
A thermometer uses a thermometric property to measure temperature. The thermometric property of a thermocouple thermometer is emf. Explain the underlined terms. Wh... show full transcript
Worked Solution & Example Answer:A thermometer uses a thermometric property to measure temperature - Leaving Cert Physics - Question 12 - 2015
Step 1
Explain the underlined terms.
Answer
The term thermometric property refers to a specific characteristic of a material that varies measurably with changes in temperature. In the context of thermocouples, the thermometric property is the electromotive force (emf), which is the voltage generated by the thermocouple in response to temperature differences.
Emf stands for electromotive force. It is a measure of the energy provided by a source of electrical energy, in this case, the voltage generated per unit charge. Emf affects how the thermocouple operates by determining the voltage output that corresponds to a particular temperature.
Step 2
What is the SI unit of temperature? Give an advantage of using this unit in scientific measurements.
Answer
The SI unit of temperature is the Kelvin (K). One advantage of using the Kelvin scale is that it is an absolute temperature scale, which does not contain negative values. This feature makes it easier to apply the gas laws, as all temperatures must be positive to maintain accuracy in physical equations.
Step 3
Describe a laboratory experiment to demonstrate the principle of operation of a thermocouple.
Answer
To demonstrate the principle of operation of a thermocouple, we can perform the following experiment:
- Materials Needed: Two different metals (e.g., copper and constantan), a thermocouple, a voltmeter, and a heat source.
- Set-Up: Connect the two metals at one end to form a junction. Connect the other ends to a voltmeter.
- Procedure: Heat one of the junctions while keeping the other junction at room temperature. As the heated junction experiences a change in temperature, the thermocouple generates a voltage that is measured by the voltmeter. This voltage corresponds to the temperature difference between the two junctions and illustrates how thermocouples function based on the principle of thermoelectricity.
Step 4
Give an advantage of using a thermocouple thermometer instead of a mercury-in-glass thermometer.
Answer
One major advantage of using a thermocouple thermometer is that it is less fragile compared to mercury-in-glass thermometers. Thermocouples are typically more durable and can withstand extreme conditions without breaking. Additionally, they can measure a wider temperature range and are safer because they do not contain toxic substances like mercury.