Kinetic theory has some important features:
. Matter is made up of particles called molecules.
The molecules remains in continues motion.
Molecules attract each other.
By heating the gas, its molecules gets high kinetic energy and start to collide more Randomly. And motion of gas molecules is increased by heating. So pressure of gas molecules increase by heating.
To kinetic energy of gas molecules goes on increasing if a gas is heated continuously. This causes the gas molecules to move faster. The collisions between atoms and molecules of the gas become so strong that they tear off the atoms. Atoms lose their elections and become positive ions. This ionic state of matter is called plasma. Plasma is also formed in gas discharge tubes when electric current passes through these tubes.
At very high temperature, the matter assumes the state of ions and electrons. This state is called plasma..
Formation of Plasma: The kinetic energy of gas molecules goes on increasing if a gas is heated continuously. This causes the gas molecules to move faster and faster. The collisions between atoms and molecules of the gas become so strong that they tear off the atoms. Atoms lose their electrons and become positive cons. The ionic state of matter is called plasma.
Plasma is highly conducting state of matter. It allows electric current to pass through it.
Heat is the energy which is transferred from one object to another due to difference of temperature between the two
The sum of kinetic and potential energies of the molecules of an object is called its internal energy
When we heat a substance, its molecular motion becomes more vigorous; which an increase in its internal energy. As a ises. The heat energy transferred to a body increases the internal energy or te molecules due to which its temperature rises,
For the exactometerement of the hotness of a substance we require an instrument called a thermometer.
Thermometers use some property of a substance, which changes appreciably with the change of temperature.
Some basic thermometric thermometer are the following. properties for a material suitable to construct a It is a good conductor of heat. ii. It gives quick response to temperature changes. iii. It has uniform thermal expansion. iv. It has high boiling point. It has low freezing point.
The liquids expand on heating. So, expansion in the volume of a liquid can be used for the measurement of temperature. This is known as Liquid-in-glass thermometer.
One such liquid which is commonly used in thermometers is mercury.
For the measurement of temperature, a scale is to be constructed which requires two reference temperatures called two fixed points.
Different scales of temperature have been constructed by assigning different numerical values to these fixed points. Three different scales are:
(1) Celsius or centigrade scale
(ii) Fahrenheit scale
(iii) Kelvin scale
In Celsius or centigrade scale, the numerical values assigned to lower and upper fixed points are 0 and 100. As the difference between these values is 100, so the space between these points is divided into 100 equal parts. Each part is known as 1°C.
In Fahrenheit scales, the lower fixed point is labelled as 32 and upper as 212. As the difference between these two numbers is 180, so in this scale the space betwe these points is divided into 180 equal parts. Each part is known as 1°F. Celsius ang Fahrenheit scales are generally used in ordinary life.
In Kelvin scale the lower and upper fixed points are labelled as 273 and 212. As the difference between these values is 100, so the width of 1K is the same as that of 1°C. The zero point of this scale is the temperature at which the molecules of substance cease to move. Their average kinetic energy becomes zero. This is known as absolute zero. Its value is-273.15°C.
Lempurple: The minimum division on the scale of athermometer is 1°C. The accuracy of its temperature measurement will be 1°C. On another thermometer the marked are 0.1°C apart. Hence, its accuracy will be up to 0.1°C and said to be more sensitive. Its measurement will be more precise than the measurement by thermometer with an accuracy of 1°C.
This refers to the span of temperature, from low to high, over which the thermometer can measure accurately. Example: A clinical thermometer designed per human body temperature has 1 narrow or short range, say from 35°C to 45°C.
This refers to a direct proportional relationship between the temperature and scale reading across entire range of measurement.
A good linear thermometer should measure equal increments on the scale corresponding to equal change in the temperature. It means marking on the scat should be evenly spaced over the whole range.
High linearity means more consistent and proportional scale readings over the entire range to ensure accuracy of measurement.
the length artes that equal temperature intervals correspond to equal changes a the length at height of the liquid column making the thermometer easy to read.
