Heat

Heat is a form of energy which gives the sensation of warmth. The sum total kinetic energy of all the vibrating molecules of a matter is heat energy. The degree of hotness or coldness of a body is called temperature.

We use heat for cooking food and keeping our body warm. We can get heat from coal, gas or electricity, and sun. The temperature of the normal human body is 98.4 degree Fahrenheit or 36.9 degree Celsius.

Differences between heat and temperature are as follows:

Heat	Temperature
The sum total kinetic energy of all the vibrating molecules of a matter is heat energy.	The degree of hotness or coldness of a body is called temperature.
Heat is measured by using calorie meter.	Temperature is measured by using thermometer.
Heat is measured in Joules or calories.	Temperature is measured in degree Celsius or degree Fahrenheit or Kelvin scale.
4.2 Joules = 1 Calorie	1 degrees Celsius = 273.15 Kelvins 1 degree Celsius = 33.8 degree Fahrenheit

 

 

 

 

 

 

 

 

Differences between clinical and lab thermometer are as follows:

Clinical thermometer	Lab thermometer
The thermometer used to measure the human body temperature is called clinical thermometer.	The thermometer which is used to measure the temperature of different chemicals, solvents and reagents is called laboratory thermometer.
The stem is graduated from 350C to 420C.	The stem is graduated from -100C to 1100C.
It has construction in its stem.	It doesn't have construction in its stem.
It is prismatic in shape.	It is round and cylindrical in shape.

 

 

 

 

 

 

 

 

 

Thermometer:

An instrument or device which is used for measuring temperature of a body is called thermometer.

Types of thermometer  on the basis of their use:

• Clinical thermometer
• Laboratory thermometer

1. Clinical thermometer:

The thermometer used to measure human body is called clinical thermometer.

Maximum minimum thermometer:

This is used to measure the maximum and minimum temperature.

Role of index in minimum and maximum thermometer:

The role of index in minimum and maximum thermometer is to enable to record the maximum day temperature to be read on the scale when the temperature rises during day time. And when the temperature falls at night, index gives the minimum temperature.

2. Laboratory thermometer:

A laboratory thermometer is a tool used in laboratories to measure temperature with a high level of accuracy. It can be partially or fully immersed in the substance being measured. A laboratory thermometer is recognizable by its long stem with a silver bulb at the end.

Mercury and alcohol:

The advantages of using Mercury instead of alcohol are as follows:

• Mercury is good conductor of heat but alcohol is bad conductor of heat.
• It expands and contracts in a uniform rate but alcohol's expansion rate is not uniform.
• It is opaque, bright, and silvery in colour which makes it easy to find the level in very fine capillary tube but alcohol is colourless so, it should be coloured before use.
• Alcohol wets the wall of capillary tube. Hence, the rise or fall of alcohol in the capillary tube is not clean and smooth.

The function of mercury in the maximum and minimum thermometer is to enable the steel index to indicate the minimum temperature at night and the function of alcohol in minimum and maximum thermometer is to enable the steel index to indicate the maximum day temperature.

Role of index in minimum and maximum thermometer:

The role of index in minimum and maximum thermometer is to enable to record the maximum day temperature to be read on the scale when the temperature rises during day time. And when the temperature falls at night, index gives the minimum temperature.

Precautions while using thermometer are as follows:

• The bulb of thermometer should come in good contact with the object or dip well in the liquid whose temperature is being measured.
• The thermometer should not touch the wall or sides of the container.
• The thermometer should be held vertically.
• The reading of mercury level in the capacity tube should be taken by taking the reading of the upper miniscus, keeping the eye on level with the meniscus.

Importance of thermometer:

• It is used to measure the temperature of the body.
• It is used to measure the temperature of the water of an aquarium.
• It is used to know the temperature of the human body and environment.