Laws of Thermodynamics and Carnot's Theorem
Summary
Things to Remember
MCQs
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Subjective Questions
Q1:
Write down some characteristics of quality of food ?
Type: Short Difficulty: Easy
<ul>
<li>The food should be fresh and Hygienic.</li>
<li>The food should be free from another unwanted chemical mixup.</li>
<li>The food should be tasty .</li>
<li>The food which we eat should supply energy to the body .</li>
<li>The food should be properly cooked.</li>
</ul>
Q2:
Write down some reason of low quality of food ?
Type: Short Difficulty: Easy
<ul>
<li>People they add more harmful colours</li>
<li>They make food by adding more oil , spicy etc.</li>
<li>They mixed low-quality substance while making food</li>
<li>People prepared by decomposed and stale food substances . etc.</li>
</ul>
Q3:
Write down the reason of low quality of food and also the measure to avoid them also ?
Type: Long Difficulty: Easy
<ul>
<li>People prepared by decomposed and stale food substances .</li>
<li>People they add more harmful colours .</li>
<li>They mixed low-quality substance while making food etc .</li>
</ul>
<p>Some measures to avoid low -quality food :</p>
<ul>
<li>Don't eat street .</li>
<li>Food should be well cooked.</li>
<li>Do not eat the food which is not healthy .</li>
<li>Do not look for the decoration of the food.etc.</li>
</ul>
Q4: What is quality food?
Type: Very_short
Difficulty: Easy
Q5: Give any two examples of low quality food.
Type: Very_short
Difficulty: Easy
Q6: Write any two characteristics of quality food.
Type: Very_short
Difficulty: Easy
Q7: What is food adulteration?
Type: Very_short
Difficulty: Easy
Q8: What is cosmetic goods?
Type: Very_short
Difficulty: Easy
Q9: Give any two examples of cosmetic goods.
Type: Very_short
Difficulty: Easy
Q10: Give any two examples of coloured foods.
Type: Very_short
Difficulty: Easy
Q11: Write effects of colouring food.
Type: Very_short
Difficulty: Easy
Q12: How does food becomes unhealthy?
Type: Very_short
Difficulty: Easy
Q13: Give any two characteristics of low quality food.
Type: Very_short
Difficulty: Easy
Videos
Characteristics and Properties of Food
Video 18 - Quality Attributes
Laws of Thermodynamics and Carnot's Theorem
Zeroth law of thermodynamics
Consider two systems A and B separated by an adiabatic wall. If these two are in contact with a system C through a diathermal wall, then by experiment it is seen that the two sysytem A and B re also in thermal equilibrium with eah other. This is known as the zeroth law of thermodynamics and can be stated as, if two systems are in thermal equilibrium with third system, then they must be in thermal equilibrium with each other.
First law of thermodynamics
It can be stated in two forms. The first form establishes the relation between the equivalence of heat energy and mechanical work. It can be stated as, if a definite quantity of heat is applied to do work, then mechanical work is obtained in same amount as heat consumed. Conversely, if mechanical work is done then each unit of heat energy is produced due to mechanical work. If Q be the amount of heat employed in a system due to which W is the work done produced, then,\begin{align*} W\propto Q \end{align*}\begin{align*} or, W=JQ \end{align*} where, J is the mechanical equivalent of heat whose value is 4.2 Joules per calorie. This form is valid only when energy supplied is used in doing work.
The first law of thermodynamics can also be considered in another form as the special case of conservation of energy. If \(dQ\) be the amount of heat given to the system, \(dU\) be the change in internal energy and \(dW\) be the small workdone, the first law says that,\begin{align*} dQ=dU+dW \end{align*}
Second law of thermodynamics
Second law of thermodynamics was introduced to remove the limitations of the first law. It is also stated in two ways:
Kelvin Planck statement: It is impossible to get a continuous supply of heat from a body by cooling it to a temperature lower than that of coldest of its surroundings.
Clausius statement: It is impossible to make heat flow from a body at a lower temperature to a body at a higher temperature without doing external work on the working substance.
These two statements are equivalent to each other.
References
Adhikari, Pitri Bhakta. A Textbook of Physics Volume-I. Kathmandu: Sukunda Pustak Bhawan, 2015.
Sears, Salinger. Thermodynamics, Kinetic Theory and Statistical Thermodynamics. New Delhi: Narosa Publishing House Pvt. Ltd., 2013.
Singhal, SS, JP Agrawal and Satya Prakash. Heat Thermodynamics and Statistical Physics. Meerut: Pragati Prakashan, 2009.
Lesson
Laws of Thermodynamics and Their Application
Subject
Physics
Grade
Bachelor of Science
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