CONDUCTIVITY OF DIFFERENT MATERIALS

Suppose an experiment is conducted by taking a container with water inside having rods of different materials attached to it. The rods have a coating of wax on them, the length of the wax is same on each rod.

Wax layer on copper melts more than wood

Now if a heating elements introduced into the water and after sometime the water will be heated. Simultaneously the wax will start melting and dripping from the rods. The wax will drip quickly from the copper rod and the amount of dripping will decrease successively for each rod, being least for the wooden one.

This is because each element has different conductivity.

Similarly If we touch the metal handle utensil we instantly remove our hand as we suddenly touched something hot.
Metals being good conductors of heat, transfers heat from one end to the other very quickly. Hence, the metal handle becomes too hot to touch.

Now if we touch the plastic or wooden handle utensil we'll be able to lift it from the oven.Plastic and wood are insulator (a bad conductor of heat) and hence even though the metallic part of the utensil gets heated, the handle remains cold enough to be touched.

H E A T......

What is the difference between a hot cup of coffee and a cold cup of coffee?Temperature is a measure the hotness of a given bodyMeasure of hotness can be done simply by touching the body.

But it is not a standard method as it is based on an individual's perception and may vary from a person to person and can be injurious if the body that we touch is very hot.
Measure of hotness should not be confused with heat irself.

The difficulty in using the sensation as a measure of hotness arises because of the fact that the terms hot and cold are relative terms and cannot be used in the absolute measurement of hotness.

Often the concepts of heat and temperature are thought to be the same, but they are not.

Perhaps the reason the two incorrectly thought to be the same is because our everyday experience suggests that when one applies heat example : putting a pot of water on the stove, then the temperature of water goes up. More heat, more temperature - so they must be the same, right? this is actually not true.

Heat is a measurement of the total energy in a substance. That total energy is made up of not only of the kinetic energies of the molecules of the substance, but is also made up of their potential energies.

Temperature, when measured in Kelvin degrees, is a number that is directly proportional to the average kinetic energy of the molecules in a substance. So, when the molecules of a substance have a small average kinetic energy, then the temperature of the substance is low. But the potential energy could be high leading to higher heat. Leading to false notion of temperature.

Therefore, there is a need of some standard for the measurement of the hotness of a body. The degree of hotness of a body is called its temperature. It is measured by devices called thermometer

How Does a thermometer work :
A common liquid in glass thermometer takes advantage of the fact that liquids generally expand more than solids as their temperatures increase. The glass envelope of the thermometer contains a fine hollow capillary with a sealed reservoir at its base that's filled with a liquid such as alcohol or mercury. If both the liquid and glass expanded equally as they became warmer, the thermometer would simply change sizes slightly as its temperature increased. But the liquid expands more than the glass and can't simply remain in place. Some of it moves up the capillary. That's why the level of liquid in the thermometer rises as the thermometer's temperature rises.

In 1954 the triple point of water-that is, the point at which the three phases of water (vapor, liquid, and ice) are in equilibrium-was adopted by international agreement as 273.16 K. The triple point can be determined with greater precision than the freezing point and thus provides a more satisfactory fixed point for the absolute thermodynamic scale. In cryogenics, or low-temperature research, temperatures as low as 0.003 K have been produced by the demagnetization of paramagnetic materials. Momentary high temperatures estimated to be greater than 100,000,000 K have been achieved by nuclear explosions (see Nuclear Weapons).

Absolute zero is a theoretical temperature. It is that temperature at which all substances have no heat energy. It is defined as zero Kelvin (0 Kelvin). 0 Kelvin is equivalent to -273.16 degrees Celsius, and -459.69 degrees Fahrenheit

In 1967, by international agreement, The Kelvin temperature scale was decided to be a scale of units rather than degrees. It is proper therefore to describe the temperature of the boiling point of water at sea level as being 373.15 Kelvin (not 373,15 degrees Kelvin), and the freezing point of water as 273.15 Kelvin (or 273.15 K)