Explain How A Liquid Thermometer Measures Temperature


Explain How A Liquid Thermometer Measures Temperature?

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. … In liquid-in-glass thermometers the thermal expansion of liquids is used for measuring the temperature!Mar 5 2019

How does a liquid thermometer measure temperature?

A thermometer measures temperature through a glass tube sealed with mercury that expands or contracts as the temperature rises or falls. The tiny size of the bulb and micro-fine size of the tube help the mercury reach the temperature of what it is measuring very rapidly.

How do you use a liquid thermometer?

Place the end of the thermometer with the reservoir of liquid in the testing medium. For example if you are testing the temperature of ice water place the reservoir in the water below the ice but not touching the bottom of the flask or cup the water is held in. This will garner a more accurate 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.

Does thermometer measure heat or temperature?

A thermometer is an instrument that measures temperature. It can measure the temperature of a solid such as food a liquid such as water or a gas such as air. The three most common units of measurement for temperature are Celsius Fahrenheit and kelvin. The Celsius scale is part of the metric system.

What do you mean by liquid thermometer?

Answer: Liquid thermometers are the one in which there is liquid filled in the cappilary. This liquid rises when in contact with an object the rise in the level of thermometer liquid shows the temperature of that object. Thermometer liquids are mercury and alcohol.

How do you measure temperature?

There are 4 ways to take (measure) a temperature:
  1. Under the armpit (axillary method)
  2. In the mouth (oral method)
  3. In the ear (tympanic method)
  4. In the rectum/bum (rectal method)

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Where are liquid thermometers used?

Mercury thermometers can be used to determine body liquid and vapor temperature. Mercury thermometers are used in households laboratory experiments and industrial applications.

Why liquids are not used for measuring high temperature?

Explanation: because mercury thermometer is used for measuring high temperature as its boiling point is 356℃ so there will be no change in volume and other physical properties .

Why are liquids used in thermometer Class 7?

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 are the properties of liquids that will make them suitable for use in liquid thermometer?

Thermometric liquids

The liquids should also have a sufficiently high boiling point so that they do not vaporize at high temperatures. Furthermore the liquid must expand evenly with the temperature in the measuring range used. Otherwise an uneven division of the scale on the thermometer would be necessary.

Why do we measure temperature?

Measuring body temperature is very important in medicine. A number of diseases are characterised by a change in body temperature. With other illnesses the course of the disease can be followed by measuring body temperature. This allows the doctor to analyse the effectiveness of treatments based on body temperatures.

How do you measure the temperature of water?

Why does liquid in a thermometer rise with hot water?

The way a thermometer works is an example of heating and cooling a liquid. When heated the molecules of the liquid in the thermometer move faster causing them to get a little further apart. This results in movement up the thermometer.

Why are liquid thermometer most commonly used?

In general a thermometer uses some measurable property of a substance which is sensitive to temperature change. Liquid in thermometers are suitable for narrow change of measurements. The most commonly used liquid is mercury.

What are the 2 liquids used in thermometers?

The two common liquids used in liquid-in-glass thermometers are alcohol (ethanol) and mercury which have melting points and boiling points of -114 C 79 C and -39 C 357 C respectively.

What are the 3 ways to measure temperature?

There are three main scales commonly used in the world today to measure temperature: the Fahrenheit (°F) scale the Celsius (°C) scale and the Kelvin (K) scale.

How do you measure outside temperature?

How to Measure Temperature Correctly
  1. Place the thermometer 5 feet above the ground (+/- 1 ft.). …
  2. The thermometer must be placed in the shade. …
  3. Have good air flow for your thermometer. …
  4. Place the thermometer over a grassy or dirt surface. …
  5. Keep the thermometer covered.

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How can you measure temperature without a thermometer?

Checking for a fever without a thermometer
  1. Touching the forehead. Touching a person’s forehead with the back of the hand is a common method of telling whether or not they have a fever. …
  2. Pinching the hand. …
  3. Looking for flushing in the cheeks. …
  4. Checking urine color. …
  5. Looking for other symptoms.

How accurate is a liquid thermometer?

Organic-Liquid-Filled Glass Thermometers contain nonhazardous liquid in a graduated scale tube which closely resembles their mercury predecessors. The accuracy of a typical glass thermometer is ±1 scale division.

Can you use a thermometer to measure water temperature?

Instant-read thermometers are a type of all-purpose food thermometer that are inserted in food for a few seconds until they get an accurate reading. … However you should never ever use a digital thermometer used to take body temperature to measure water.

Which of the following liquid is used for measuring the temperature in ordinary thermometer?

Mercury is liquid at room temperature. Mercury expands on the slightest change in temperature. It has a shiny appearance and does not stick to the glass. So this liquid is used for measuring the temperature in ordinary thermometers.

Why do thermometers use liquid instead of a solid or gas?

Liquids are used in thermometers because they expand and contract with temperature changes and they take on the shape of a container without filling it. Solids do not work in thermometers because they do not take on the shape of the container.

Why is alcohol used instead of water in thermometers?

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.

What are the three most commonly used temperature scales?


There are three temperature scales in use today Fahrenheit Celsius and Kelvin. Fahrenheit temperature scale is a scale based on 32 for the freezing point of water and 212 for the boiling point of water the interval between the two being divided into 180 parts.

Why do we use mercury or alcohol as thermometer liquid?

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.

How is heat transferred in liquids?

When the object is a fluid heat can be transferred from the fluid to another object by flow of the fluid on the surface of the object. This type of heat transfer is called convection. Convection can transfer larger amounts of heat than conduction.

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Why is mercury and alcohol used in thermometers?

There is a technical reason for using mercury in clinical thermometers. Mercury has a greater coefficient of thermal expansion than alcohol. This means a column of mercury will expand and rise more than a column of alcohol for the same temperature change. As a result you can get finer readings with mercury.

Why does the liquid in the thermometer expand and contract when temperature changes?

When a liquid is hot the molecules move around faster and bump into each other and the walls of the container more often and harder than slower moving molecules do. One result of this is that a hot liquid will expand in direct proportion to its temperature.

How the electrical resistance thermometer is used in temperature measurement for industrial purpose?

Function. Resistance thermometers are constructed in a number of forms and offer greater stability accuracy and repeatability in some cases than thermocouples. While thermocouples use the Seebeck effect to generate a voltage resistance thermometers use electrical resistance and require a power source to operate.

What makes a liquid in glass thermometer sensitive to a small change of temperature?

For a small change of temperature more change in the height of the liquid column. The bulb should be of moderate size and the capillary tube should not be extremely narrow. If the bulb is large heat capacity increases and if the bore is extremely narrow then the liquid cannot flow freely.

What is temperature explain?

Temperature is the measure of hotness or coldness expressed in terms of any of several scales including Fahrenheit and Celsius. Temperature indicates the direction in which heat energy will spontaneously flow—i.e. from a hotter body (one at a higher temperature) to a colder body (one at a lower temperature).

What are the 4 types of temperature?

The Four Types of Temperature Scales
  • Fahrenheit Scale. ••• The Fahrenheit scale of temperature is the common form of temperature measurement used in the United States and some parts of the Caribbean. …
  • Celsius Scale. ••• …
  • Kelvin Scale. ••• …
  • Rankine Scale. •••

What is temperature really a measure of and how do we know?

Temperature is a measure of the average kinetic energy of the particles in an object. Everybody has used a thermometer at least once in their lives but even without one our bodies are decent sensors for measuring how hot or cold things are upon contact.

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