Thermometer

 How to make thermometer

A thermometer is a specific instrument used to measure how hot or cold something is.

thermometer

 We can measure the air on a hot summer's day; we can measure body temperature or even the water temperature of a swimming pool. Thermometers are used in numerous ways. 
To make your very own thermometer, first assemble the materials listed below. 
 Manual thermometer Materials needed:
 1. a narrow necked bottle (a small soda bottle works well) 
2. a straw 
3 some clay 
 4 food colouring 
 5- Hot plate 
6- Water 
7- A pot 
8- Ice cubes 

 Procedure to make thermometer

Take your narrow necked bottle and fill it about 3/4 full of water. Add a few drops of food colouring and shake gently, being careful to cover the opening to avoid a spill. Place a straw in the bottle submerging one end in the colourec water. Use clay to hold the straw in place. It is essential that there is an airtight seal between the straw and the bottle so be sure' mold the clay careful.

How to make thermometer

 Now put your bottle in a pot of water and place it on a hot plate. Heat the water in the pot to the boiling point. Record what happens now. Next remove the bottle from the pot. Use an oven mitt so yoi don't burn yourself. Allow the bottle to cool somewhat. Now place the bottle back in the pot. Surround it with ice cubes and observe the results.

Thermometer

 Thermometer it is an instrument to measure temperature of body and also atmosphere. It consists of a capillary tube, attached with this bulb. In an ordinary thermometer, the thermal characteristics of expansion and contraction of mercury( Mercury ialso name of a planet which moves around the sun like our earth) is used to measure the temperature. Due to narrow bone of capillary tube, a small change in the volume of mercury becomes significantly visible.

 Establishing a temperature scale:

 For establishing a temperature scale we need two standard temperature.
 1-Boiling point of water 
 2-Melting point of water
 In order to find out the position of mercury thread in the capillary tube of a thermometer at the melting point of ice, we place its bulb in a vessel containing small pieces of melting ice after some time, the mercury thread becomes stationary at a certain point in the capillary tube.
 This point is marked by a file. This mark indicates the temperature of the boiling point of ice. In order to find out the position of mercury thread at the boiling point of water, the bulb of the thermometer is placed in steam above boiling water at one atmospheric pressure. The mercury thread rises and finally comes at rest at a certain point which is marked by a files. The work indicates the temperature of boiling point of water. Different scales of temperature measurement have been formed, which are as follows. 
Celsius scale 
 Fahrenheit scale 
Kelvin scale 
 Celsius Scale: 
 On this scale, the mark corresponding to melting point of ice is denoted as 0°C and that corresponding to boiling point of water as 100°C. The distance between these two marks is divided in 100 equal parts. Each part indicates one degree calcium (1°C)- According to size of this degree, the temperature range of thermometer may extend below 0°C and above 100°C. 1-Fahrenheit 
 2-Celsius 
 3-Kelvin 
 On this scale, the mark indicating the melting point of water is denoted as 32°F and the mark for boiling point of water as 212°F. The distance between the two mark is divided into 180° equal parts. Each part is know as one degree Fahrenheit (1 °F). 
 If a certain temperature reads C in Celsius scale and F in Fahrenheit scale, the two readings are related as By the help of this equation the reading of a temperature in Celsius scale can be converted into Fahrenheit scale and vice-versa. Kelvin Scale: -273°C is the lowest possible temperature. In Kelvin scale this temperature is denoted by oK. The size of division in Kelvin scale is the same as that in Celsius scale. 
Thus the melting point of ice in Kelvin scale is 273K and the boiling point of water is 373 K. If C° is the value of a certain temperature in Celsius scale, its equivalent value T in Kelvin scale is given by T = C°+273 Note the small circular symbol of degree is not used on Kelvin scale. When water is cooled down, its volume decreases. This continues upto 4°C. When it cooled further down, its volume starts increasing and its density decreases. 
Since the temperature of ice of 0°C, therefore its density is less than that of water. This is why the ice floats on the surface of water. Give examples of thermal expansion from daily life.
 Following are the examples of thermal expansion from daily life. 1-Overhead telephone or electricity wires between two poles are given a certain amount of sag so that they can contract in winter without snapping. 
2-Two sections of a railway track are not joined together by welding. Instead they are laid with gaps between them.
 Using fish plates fastened by nuts and bolts which are able to slide along the oval holes of the plates. When the rails expand or contract, they slide along the fish plates, thus preventing the buckling of tracks. If there are no gaps, the expansion of the rail will cause it to buckle Iron girders are used in the construction of bridges and roof structure of big buildings.
 One end of these girders is places on rollers so that it can move forward or backward .
The temperature of:
 The center of the sun = 107K. 
The out surface of sun = 6x106K
 When a bi-metallic plate is heated or cooled, it bends the curvature thus produced is used to control the temperature of electric iron, ovens, refri gerator, air conditioners, fan heaters etc. 
 On cooling, the volume of water decreases the decrease continues upto 4°C after which the water expands on further cooling. So, the density of water is maximum at 4°C. Normally the size of solid objects increases on heating. The volume of liquids increases on heating. 
The volume of gases increases on heating. In an ordinary thermometer the temperature is measured by using the property of thermal expansion and contraction of mercury. 
On Celsius scale the melting point of ice is denoted by 0°C and boiling point of water by 100°C. On the thermometer, the distance between the marks of these two temperatures is divided in 100 equal parts. Each part is known as 1°C. On Fahrenheit scale, the melting point of ice is denoted by 32°F and the boiling point of water as 212°F. 
On the thermometer, the distance between the marks of these two temperature is divided in 180 equal parts and each part is known as one degree Fahrenheit (1 °F). 
The lowest attainable temperature which is 273°C is denoted as °K in kelvin scale. The size of the division is the same as in Celsius scale. In this scale the melting point of ice is 273 K and boiling point of water is 373 K. If the value of a certain temperature is °C in Celsius scale, °F is Farenheit scale and T in Kelvin scale, these values can be converted into each other by the following two equation. °F= °C + 32 and T = °C + 273