What is the liquid-in-glass thermometer?
Usually, mercury and petrolate are the most common fluids in this kind of thermometer. Mercury and petrolate usually can measure temperature in a range of −40 to +900°C and −200 to +260°C, respectively [2].
How does liquid-in-glass thermometer work?
Liquid-in-glass thermometers are based on the principle of thermal expansion of substances. A liquid in a glass tube (called a capillary) expands when heated and contracts when cooled. A calibrated scale can then be used to read off the respective temperature that led to the corresponding thermal expansion.
What makes a liquid-in-glass thermometer sensitive to a small change of temperature?
What makes a clinical thermometer suitable for measuring small changes in body temperature? The amount of mercury in the bulb is small. The bore of the capillary tube is narrow. The capillary tube is long.
What is the physical property that changes with temperature in a liquid-in-glass thermometer?
thermal expansion
A thermometer has a liquid in a very narrow tube, which when heated will expand and move up the tube. If you cool the liquid down, then the liquid will contract and move back down the tube. So the physical property used in a thermometer is thermal expansion.
What is mercury liquid-in-glass thermometer?
In a mercury thermometer, a glass tube is filled with mercury and a standard temperature scale is marked on the tube. With changes in temperature, the mercury expands and contracts, and the temperature can be read from the scale. Mercury thermometers can be used to determine body, liquid, and vapor temperature.
Why are liquids used in a thermometer?
It is because the liquids like mercury and alcohol expand uniformly on increasing temperature and also contracts uniformly on decreasing the temperature. So, it gives us the accurate measure of the temperature. That’s why liquids are used in the thermometer not solids or gases.
What is the function of a liquid thermometer?
The Liquid-in-Glass Thermometer is a type of a thermometer used to measure temperature. The thermal expansion of the liquid is the principle used to measure the temperature in the thermometer. When the temperature increases, the liquid expands and then rises in the capillary tube in the thermometer.
Which factors affect the sensitivity of thermometer Igcse?
Some of the factors which increase sensitivity are:
- Using a thermometer with a smaller glass bulb, as a smaller bulb contains less liquid and therefore, absorbs heat in a shorter time.
- Using a narrow tube, as a small change in volume results in the liquid moving a larger distance along the tube.
Why mercury is used in thermometers?
Mercury is the only one in liquid state at room temperature. It’s used in thermometers because it has high coefficient of expansion. Hence, the slightest change in temperature is notable when it’s used in a thermometer. It also has a high boiling point which makes it very suitable to measure higher temperatures.
What property of a liquid such as mercury is used in a liquid-in-glass thermometer?
Which physical property is used to measure temperature in a liquid-in-glass thermometer Igcse?
thermal expansion properties
The liquids used in liquid-in-glass thermometers are chosen for their thermal expansion properties: They expand linearly with temperature.
Why do we use mercury and alcohol in liquid-in-glass thermometer?
Answer. Alcohol thermometers are used rather than mercury thermometers in very cold regions because alcohol has a lower freezing point than mercury. If it freezes it won’t move in the tube, so a liquid must be used that has a freezing point that’s lower than the temperature it’s measuring.
How does a liquid in glass thermometer work?
A liquid-in-glass thermometer consists of a thin glass capillary tube containing a liquid that expands with temperature At one end of the tube is a glass bulb, containing a larger volume of the liquid which expands when heated, moving into the narrower tube
How is the temperature of a liquid measured?
At one end of the tube is a glass bulb, containing a larger volume of the liquid which expands when heated, moving into the narrower tube A scale along the side of the tube allows the temperature to be measured based on the length of liquid within the tube Sensitivity is another word for precision.
Why are Mercury and alcohol used in thermometers?
When the glass bulb is is heated, the liquid in the bulb starts to expand up the capillary tube. Commonly Mercury and Alcohol (coloured) are used because Mercury boils at 357℃ and freezes at -39℃. Alcohol boils at 78℃ and freezes at -115℃, therefore Alcohol is more suited to low temperatures and Mercury is suitable for higher temperatures.
Which is more sensitive liquid in glass or thermocouple?
Thermocouples are not as sensitive as liquid-in-glass thermometers, but because the metals have high melting points, they can be used to measure very high temperatures Thermocouples are also very responsive to rapidly changing temperatures
