{"id":12485,"date":"2026-05-14T10:48:20","date_gmt":"2026-05-14T10:48:20","guid":{"rendered":"https:\/\/www.vedprep.com\/exams\/?p=12485"},"modified":"2026-05-14T11:19:08","modified_gmt":"2026-05-14T11:19:08","slug":"first-law-of-thermodynamics-2027","status":"publish","type":"post","link":"https:\/\/www.vedprep.com\/exams\/iit-jam\/first-law-of-thermodynamics-2027\/","title":{"rendered":"First law of thermodynamics For IIT JAM 2027"},"content":{"rendered":"

First law of thermodynamics<\/strong> For IIT JAM states that energy cannot be created or destroyed, only converted from one form to another. This fundamental principle is crucial for solving thermodynamics problems in IIT JAM exams.<\/p>\n

Syllabus – Thermodynamics<\/strong><\/h2>\n

Thermodynamics isn’t just a chapter; it’s a massive chunk of the IIT JAM Physics<\/strong><\/a> syllabus. Usually tucked into the kinetic theory and thermodynamics section, it\u2019s a high-yield area. While legends like Halliday-Resnick-Walker or Knight are great for building a deep foundation, remember that the JAM exam loves to test how you apply these concepts such as First law of thermodynamics <\/strong>to real systems.<\/p>\n

At VedPrep<\/b>, we\u2019ve noticed that students who master the First law of thermodynamics<\/strong> early on find it much easier to tackle tougher topics like entropy or heat engines later. Whether you\u2019re also eyeing GATE or CUET PG, this is the ground floor of your preparation.<\/p>\n

First Law of Thermodynamics: A Fundamental Principle<\/strong><\/h2>\n

Think of the First Law as a bank account for energy. If you deposit some “cash” (heat, Q<\/span>) and the system spends some on “shopping” (work, W<\/span>), whatever is left over stays in the “savings account” (internal energy, \u0394U<\/span>).<\/p>\n

The math is simple: \u0394U = Q – W<\/span><\/p>\n

In physics, we usually say W<\/span>\u00a0is the work done by<\/i> the system. If the system expands, it\u2019s doing work (spending energy), so we subtract it. If you compress it, you\u2019re doing work on<\/i> it, and that internal energy goes up.<\/p>\n

Worked Example: Thermodynamic Process<\/strong><\/h2>\n

Let’s look at a quick problem on First law of thermodynamics<\/strong>. Say you have a gas in a cylinder. Its internal energy starts at 500 J<\/span>\u00a0and ends up at 700 J<\/span> after a process. During this time, it sucks up 300 J<\/span>\u00a0of heat. How much work did the gas actually do?<\/p>\n

    \n
  1. \n

    Find the change:<\/b> \u0394U = Ufinal<\/sub> – Uinitial<\/sub> = 700 J – 500 J = 200 J<\/span>.<\/p>\n<\/li>\n

  2. \n

    Plug it in:<\/b> 200 J = 300 J – W<\/span>.<\/p>\n<\/li>\n

  3. \n

    Solve:<\/b> W = 100 J<\/span>.<\/p>\n<\/li>\n<\/ol>\n

    Therefore, the work done by the system during this thermodynamic process is 100 J.<\/p>\n

    Common Misconception: Energy Conservation<\/strong><\/h2>\n

    A common trap is thinking “conservation” means nothing changes. That\u2019s not true. Imagine a fictional scenario where you\u2019re rubbing your hands together on a cold morning. You\u2019re putting in mechanical work, which turns into heat. The total energy in that little “hand-system” is conserved, but the type<\/i> of energy is flipping from motion to thermal.<\/p>\n