Thermometer How Does It Work

Thermometer How Does It Work?

A thermometer measures temperature through a glass tube sealed with mercury that expands or contracts as the temperature rises or falls. … As temperatures rise the mercury-filled bulb expands into the capillary tube. Its rate of expansion is calibrated on the glass scale.

How does a thermometer work for fever?

Digital thermometers work by using heat sensors that determine body temperature. They can be used to take temperature readings in the mouth rectum or armpit. When assessing digital thermometer readings keep in mind that armpit (axillary) temperature runs about ½ to 1°F (0.6°C) cooler than oral readings.

How do you measure temperature with a thermometer?

Axillary method (under the armpit)
  1. Place the tip of the thermometer in the centre of the armpit.
  2. Tuck your child’s arm snugly (closely) against their body.
  3. Leave the thermometer in place for about 1 minute until you hear the “beep”
  4. Remove the thermometer and read the temperature.

What does a thermometer actually measure?

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.

How does a modern thermometer work?

Digital thermometers contain a small computing mechanism and a resistor. A change in temperature causes the sensor to notice a change in resistance. The computer converts the difference in resistance into a difference in temperature and offers a digital readout in degrees.

Is 37.5 a fever?

A high temperature is usually considered to be 38C or above. This is sometimes called a fever. Many things can cause a high temperature but it’s usually caused by your body fighting an infection.

What temperature is a fever?

The following thermometer readings generally indicate a fever: Rectal ear or temporal artery temperature of 100.4 (38 C) or higher. Oral temperature of 100 F (37.8 C) or higher. Armpit temperature of 99 F (37.2 C) or higher.

Is a temp of 35 normal?

Normal body temperature is around 98.6 F (37 C). Hypothermia (hi-poe-THUR-me-uh) occurs as your body temperature falls below 95 F (35 C).

What are 3 types of thermometers?

What Are the Different Ways a Thermometer Can Be Used?
  • Axillary Thermometers (under your arm)
  • Oral Thermometers (under your tongue)
  • Tympanic Thermometers (in your ear)
  • Rectal Thermometers (in your rectum)
  • Temporal Artery or Infrared Thermometers (across your forehead)

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What is your normal temperature?


The average normal body temperature is generally accepted as 98.6°F (37°C). Some studies have shown that the “normal” body temperature can have a wide range from 97°F (36.1°C) to 99°F (37.2°C). A temperature over 100.4°F (38°C) most often means you have a fever caused by an infection or illness.

How are thermometers made?

A thermometer is usually made up of a small hollow glass tube. At the bottom of the tube is a bulb which holds a liquid such as alcohol or mercury. When there is an increase in heat the liquid inside the bulb expands pushing up into the tube. A decrease in heat lets the liquid contract moving down the tube.

Can a thermometer measure heat?

Despite its name however a thermometer does not actually record heat but rather temperature. … Temperature is a measure of the average kinetic energy of the molecules within a substance.

What is the red liquid in a thermometer?


Mercury is a silver-white to gray substance. If your thermometer is filled with a red liquid your thermometer contains red dyed alcohol or mineral spirits and not mercury.

Why does the liquid inside the thermometer rise?

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.

Is a thermometer a transducer?

A thermometer senses and converts temperature into a readable output thus it is a sensor. … The thermometer is both a transducer (usually a thermocouple that transfers heat energy to voltage) and a sensor (quantifies the transducer output with a readable format).

Why do thermometers use alcohol instead of water?

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 long does temperature last with Covid?

If you have mild disease fever is likely to settle within a few days and you are likely to feel significantly better after a week – the minimum time at which you can leave self-isolation is ten days.

Does paracetamol bring down a fever?

How does paracetamol work? Paracetamol seems to work by blocking chemical messengers in the brain that tell us we have pain. Paracetamol also reduces fever by affecting the chemical messengers in an area of the brain that regulates body temperature.

Can you have a fever without a high temperature?

Feeling feverish or hot may be one of the first signs of having a fever. However it’s also possible to feel feverish but not be running an actual temperature. Underlying medical conditions hormone fluctuations and lifestyle may all contribute to these feelings.

Is 36.9 a fever?

A normal adult body temperature when taken orally can range from 97.6–99.6°F though different sources may give slightly different figures. In adults the following temperatures suggest that someone has a fever: at least 100.4°F (38°C) is a fever. above 103.1°F (39.5°C) is a high fever.

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What are the first signs of a fever?

The main symptoms of a fever include:
  • Elevated temperature (above 100.4°).
  • Chills shivering shaking.
  • Body aches and headaches.
  • Fatigue (tiredness).
  • Intermittent or constant sweating.
  • Flushed complexion or hot skin.

Is 37.2 a fever?

What are the symptoms of a fever? Normal body temperature ranges from 97.5°F to 98.9°F (36.4°C to 37.2°C). It tends to be lower in the morning and higher in the evening. Most healthcare providers consider a fever to be 100.4°F (38°C) or higher.

Is 95.6 a normal temperature?

When in good health the human body’s normal temperature is typically between 97 to 99 degrees. If your body temperature is above 100 you may have a fever caused by a virus or bacterial infection. If your body temperature is below 97 to 99 degrees there are a few explanations.

What temperature is too low for a person?

Body temperature below 95°F (35°C) is considered abnormally low and the condition is known as hypothermia. This happens when your body loses heat faster than it can produce heat. Hypothermia is a medical emergency which if left untreated can lead to brain damage and cardiac failure.

Why is my body temp so low?

Why is my body temperature low? Studies show that core body temperature decreases with age. Hypothyroidism or an underactive thyroid can also slow down metabolism which can lead to a drop in body temperature. If your core body temperature dips down to 95 F (35 C) or lower that’s considered hypothermia.

Is 99 a fever?

A factor that needs to be considered is how you took your temperature. If you measured your temperature under your armpit then 99°F or higher indicates a fever. Temperature measured rectally or in the ear is a fever at 100.4°F (38°C) or greater. An oral temperature of 100°F (37.8° C) or more is a fever.

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How many thermometer do we have?

Common types of thermometers are Medical thermometers Infrared thermometers Mercury thermometers thermocouple thermometers laboratory thermometers Bimetallic strip thermometers Pyrometers etc.

How many thermometers are there?

Three types of thermometers are alcohol liquid crystal and infrared radiation (pyrometer). The three main temperature scales are Celsius Fahrenheit and Kelvin. Temperatures can be converted from one scale to another using temperature conversion equations.

What is a high temp for Covid?

Symptoms of coronavirus

continuous cough. fever/high temperature (37.8C or greater) loss of or change in sense of smell or taste (anosmia)

Is a temperature of 37.8 normal?

A healthy internal body temperature falls within a narrow window. The average person has a baseline temperature between 98°F (37°C) and 100°F (37.8°C). Your body has some flexibility with temperature. However if you get to the extremes of body temperature it can affect your body’s ability to function.

Is 37.1 a normal temperature?

A low-grade fever for adults and children is when your body temperature is elevated slightly above normal. This is generally between 98.8°F (37.1°C) and 100.3°F (38°C). People with high-grade fevers should seek medical advice. For adults this is an oral temperature of 103°F (39.4°C).

What is inside of 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.

What metal is in a thermometer?


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.

How was thermometer invented?

In 1714 Dutch scientist and inventor Daniel Gabriel Fahrenheit invented the first reliable thermometer using mercury instead of alcohol and water mixtures. In 1724 he proposed a temperature scale which now (slightly adjusted) bears his name.

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