E ExamMaster

CBSE Class 11 · Physics

Thermal Properties of Matter

Official NCERT chapter from Physics Part I–II (book code keph1). ExamMaster notes are original teaching at CBSE Class 11 depth.

This lesson follows the official chapter “Thermal Properties of Matter” in Physics Part I–II. The words below are ExamMaster’s teaching, not a paste from the book. Use the NCERT chapter for the classroom sequence; use these notes to hold the idea without copying exercises or figures.

  • CBSE Class 11
  • Medium level
  • 9 concepts

1Temperature and heat

Temperature is how hot on a scale; heat is energy that moves because of a temperature difference. A 40 °C mug can hold more or less energy than a 40 °C thimble — temperature matched, heat-capacity later. Mixing the two words is the miss.

Saying “this object has more temperature” when you mean more heat is a swap.

Figure. Temperature is the reading on each body. Heat is the energy that crosses from the hotter body to the colder one because those readings differ. Contact continues until both read the same temperature; the arrow is the transfer, not a second temperature.

How it works

  1. Name a scale-reading as temperatureThe hotness-number.
  2. Name energy on the move as heatThe transfer.
  3. Keep them two headingsT versus Q.

2Measurement of temperature

Measurement of temperature uses a taught scale and a property that changes (a column, a resistance — as named). Ice and steam points if the lesson used them are the marks. A forehead-feel is not this measurement.

A colour-mood “looks hotter” is not a scale.

Figure. A thermometer is a calibrated thermometric property. Ice point and steam point are the same two physical states on every school scale: 0°C / 32°F / 273 K and 100°C / 212°F / 373 K. The dashed rules are those two fixed points, not extra temperatures.

How it works

  1. Name the scale and the propertyThe tool.
  2. Read the markThe measurement.
  3. Refuse a feel-only as the numberSchool size.

3Ideal-gas equation and absolute temperature

Ideal-gas equation PV = nRT (or the taught form) links P, V, T with T on an absolute scale (kelvin). 0 °C is 273 K as the school bridge. Absolute zero is the scale’s zero, not “no molecules”.

Using T=0 for ice in PV=nRT is a miss if the write needed kelvin.

Figure. At fixed volume, pressure is proportional to absolute temperature: PV=nRT becomes P\propto T. On a Celsius axis the same line is P=P_0(1+t/273) and hits P=0 at t=-273^{\circ}\mathrm{C}. That intercept is absolute zero, the origin of the kelvin scale, not a laboratory point you measure with a mercury column.

How it works

  1. Convert °C to K if the equation needs absolute TThe prepare.
  2. Write PV=nRTThe link.
  3. Keep T=0 K as the absolute zero, not 0 °CThe scale.

27 °C to kelvin

Write 27 °C as an absolute temperature for PV=nRT.

  • Add 273300 K
  • Not27 K
  • ReadAbsolute scale

Pro tip. Ice is ~273 K, not 0 in this equation.

4Thermal expansion

Thermal expansion: a length grows ΔL = α L ΔT as taught. A 2.0 m rod, α=1.2×10⁻⁵ /K, ΔT=50 K → 1.2 mm. Area and volume twins if named. A gap in a rail is this heading’s use.

Using ΔT in °C-sized steps is fine (same step as K); using T=50 °C as if it were ΔT when the start was 20 °C is a miss.

Figure. Linear expansion is the extra length of a rod that was already L. The school relation is \Delta L=\alpha L\Delta T: the change is proportional to the original length and to the temperature rise. The drawing exaggerates \Delta L so the increment is visible; a real metal rod grows by parts in a thousand, not by a third of L.

How it works

  1. Name L, α, ΔTThe given.
  2. Write ΔL = α L ΔTThe grow.
  3. Keep the unit on α as 1/KExpansion.

5Specific heat capacity

Specific heat capacity c is energy per mass per degree: Q = m c ΔT. 2 kg, c=4000 J/(kg·K) as a school water-ish, ΔT=5 K → 4×10⁴ J. A large c means a stubborn temperature. c is not latent heat.

Using Q=mc with no ΔT is a miss.

Figure. Specific heat capacity c is the heat that raises 1 kg by 1 K. Water’s 4.18 sits far above the metals, so the same mass and the same \Delta T need far more Q for water: Q=mc\Delta T. Copper looks “easy to heat” because its bar is short, not because heat is a different quantity.

How it works

  1. Name m, c, ΔTThe given.
  2. Write Q = m c ΔTThe heat to change T.
  3. Keep J/(kg·K) on cSpecific.

6Calorimetry

Calorimetry is an energy-account: heat lost by one part equals heat gained by another if the lesson ignored leaks. Hot 0.2 kg water at 70 °C into 0.2 kg at 20 °C (same c) settles near 45 °C. A leaky cup fails the equal-account.

Averaging 70 and 20 without masses is a miss if masses differ.

Figure. Calorimetry balances energy, not temperatures. Heat lost by the hot body equals heat gained by the water and calorimeter: m_1c_1(T_1-T_f)=m_2c_2(T_f-T_2). The mixture temperature T_f sits between T_1 and T_2; it is not their average unless the mc values match.

How it works

  1. Write m c ΔT lost = m c ΔT gainedThe account.
  2. Solve the unknown T or cThe mix.
  3. Name a leak if the numbers refuse to closeHonest.

7Change of state

Change of state uses latent heat: Q = m L at the boil or melt, temperature stuck while the phase changes (as taught). 0.1 kg of ice at 0 °C needs mL before it becomes 0 °C water. L is not c.

Using Q=mcΔT through a melt with ΔT=0 as if Q=0 skips L.

Figure. While a pure substance changes state, added heat goes into latent heat and the temperature holds. The first plateau is melting at 0°C, the second is boiling at 100°C. The boil step is drawn longer because L_v is much larger than L_f. Sloped segments are sensible heat (Q=mc\Delta T) for ice, water, then steam. The Q axis is schematic, not a millimetre scale of kilojoules.

How it works

  1. See a phase change at constant TThe gate.
  2. Write Q = m LThe latent.
  3. Then Q=mcΔT only after the phase is doneTwo writings.

8Heat transfer

Heat transfer paths: conduction through a material, convection by a moving fluid, radiation with no need of a rod or a loop — as taught. A metal spoon in tea is conduction; a room’s ceiling-warm can be convection; the Sun on skin is radiation. Path is the how, not a new energy.

Calling every warm “radiation” is a rush.

Figure. Heat travels three school ways. Conduction is Q along a solid from the hot end to the cold end. Convection is bulk motion of a fluid (up on the warm side, down on the cool side). Radiation is energy leaving a surface even across empty space — drawn as outgoing arrows, not as a sun disc.

How it works

  1. Name the path: through-stuff, riding-fluid, or no-touchThe how.
  2. Hang conduction / convection / radiationThe sort.
  3. Keep Q as the energy, the path as the jobTwo headings.

9Newton’s law of cooling

Newton’s law of cooling: the rate of temperature-drop is proportional to (T − T_surroundings) as taught, for the school range. A hotter cup cools faster at first. It is a rate-law, not “all cooling is Newton”.

A freezer-story with a phase change is not this rate alone.

Figure. Newton’s law of cooling: the temperature falls faster when the body is much hotter than its surroundings, dT/dt=-k(T-T_s). The solid curve is T=20+60e^{-2.5t/t_{\mathrm{end}}} approaching the dashed room line T_s=20^{\circ}\mathrm{C}. The slope flattens as T-T_s shrinks; it is not a straight line down to zero.

How it works

  1. Name T and T_sThe gap.
  2. Say dT/dt ∝ −(T−T_s) as taughtThe law.
  3. Read a bigger gap as a faster dropThe use.
Q = m c ΔT is for
  1. A temperature change of one phase
  2. A melt at constant T (that is mL)
  3. A unit convert

c versus L are different writings.

Notes

  • Mapped to the official NCERT chapter “Thermal Properties of Matter”. Original teaching only — no textbook sentences.
  • Science here is Physics, Chemistry and Biology ideas at this class, never a language or social-science chapter.

Formulas

  • PV=nRT (T in K)
  • ΔL=αLΔT
  • Q=mcΔT
  • Q=mL (phase change)

Recap

Hold these pegs from the official chapter “Thermal Properties of Matter”. The wording is ExamMaster’s teaching, not a textbook recap.

Temperature and heat
Temperature is how hot on a scale; heat is energy that moves because of a temperature difference.
Measurement of temperature
Measurement of temperature uses a taught scale and a property that changes (a column, a resistance — as named).
Ideal-gas equation and absolute temperature
Ideal-gas equation PV = nRT (or the taught form) links P, V, T with T on an absolute scale (kelvin).
Thermal expansion
Thermal expansion: a length grows ΔL = α L ΔT as taught.
Specific heat capacity
Specific heat capacity c is energy per mass per degree: Q = m c ΔT.
Calorimetry
Calorimetry is an energy-account: heat lost by one part equals heat gained by another if the lesson ignored leaks.

Practise Thermal Properties of Matter

Reading is free and needs no account. Practice, mocks and progress live in the app.

  • A 4-question practice set that ends the chapter
  • 1 quick check with worked explanations
  • Timed mocks scored with the real marking scheme
  • Readiness tracked per topic, kept on your device
Continue with Google — freeNo card, no trial. Works offline once installed.