Thermal Properties of Matter
Class 11 · Physics
4 ideas in Class 11 Physics, explained in plain words, with games and quizzes to practise.
Temperature, Heat and Expansion
Part of: Heat, Temperature and Calorimetry
Temperature reads how hot, heat is energy on the move, and Kelvin counts from absolute zero. Warming stretches length, area and volume in fixed ratios set by the material. Water breaks the rule near freezing, growing densest at 4 degrees.
Why it matters. Bridges, lids and lakes all breathe with temperature. Mixing up heat with temperature ruins every thermal prediction.
Formulas
- K = C + 273.15
- Length growth = L x alpha x rise
- Area growth uses 2 alpha; volume growth uses 3 alpha.
Key words
- Temperature
- : How hot a body is, read from average molecular motion.
- Heat
- : Energy on the move from hotter to colder.
- Kelvin scale
- : Counting temperature from absolute zero.
- Linear expansion
- : Length growth in fixed ratio to rise.
- Anomalous expansion
- : Water swelling below 4 degrees instead of shrinking.
Try it in two minutes
- Warm a lid to open a tight jar.
- Mark a rod, warm it and remeasure.
- Chill water and watch ice float.
Try at home. Compare lid loosening with hot versus cold water.
Specific Heat and Calorimetry
Part of: Heat, Temperature and Calorimetry
Heating needs mass times specific heat times rise. Water's huge capacity steadies coasts and bodies. In an insulated mix, the hot side's loss exactly pays the cold side's gain, fixing the final temperature between them.
Why it matters. Cooking times, climates and lab mixtures all follow this balance. One equation predicts the meeting temperature.
Formulas
- Q = m c (temperature change)
- Lost heat = gained heat in an insulated mix.
Key words
- Specific heat
- : Heat needed per unit mass per degree.
- Heat capacity
- : Heat needed per degree for a whole body.
- Calorimetry
- : Measuring heat flow by temperature change.
- Thermal equilibrium
- : The shared final temperature of an insulated mix.
Try it in two minutes
- Warm equal cups of water and oil equally and compare.
- Mix hot and cold water and predict the middle.
- Measure and check the prediction.
Try at home. Mix bath water to a target temperature by calculation.
Change of State
Part of: State Changes and Heat Flow
Melting and boiling stall the thermometer while heat breaks bonds: mass times latent heat each way. Warming, melting, warming, boiling stack into the full journey from ice to steam. Pressure shifts the melting point, letting wires cut ice that refreezes behind them.
Why it matters. Cooking, skating, sweating and weather all hinge on hidden heat. Flat graph sections are the giveaway.
Formulas
- Q = m L for melting or boiling
- The ice-to-steam journey stacks warming, melting, warming, boiling.
Key words
- Latent heat
- : Heat for state change with no temperature change.
- Fusion
- : Melting, needing mass times latent heat of fusion.
- Vaporisation
- : Boiling, needing mass times latent heat of vaporisation.
- Regelation
- : Melting under pressure and refreezing when released.
Try it in two minutes
- Melt ice while logging temperature each minute.
- Spot the flat melting section.
- Boil water and spot the second flat.
Try at home. Time ice melting versus water warming and compare.
Heat Transfer and Cooling
Part of: State Changes and Heat Flow
Conduction creeps through solids skid by skid, flowing faster with conductivity, area and drop, slower with length. Fluids carry heat by moving; empty space sends it as radiation. Hot bodies cool faster when farther above their surroundings.
Why it matters. Pots, homes, reactors and weather all balance these three roads. Conductivity tables and cooling rates size them.
Formulas
- Heat current H = K A (temperature drop) / L
- Steady state: inflow equals outflow.
Key words
- Conduction
- : Heat creeping through solids without bulk motion.
- Convection
- : Heat carried by moving fluid.
- Radiation
- : Heat sent as waves needing no medium.
- Thermal conductivity
- : How fast a material conducts heat.
- Newton's law of cooling
- : Bodies farther above surroundings cool faster.
Try it in two minutes
- Hold a metal and a wooden spoon in hot water.
- Watch warm air rise above a heater.
- Feel sun warmth with no air path.
Try at home. Rank spoons by handle warmth in hot tea.
What your child will practise
- Change of State: Space Quick Fire (Quick Fire)
- Heat Transfer and Cooling: Ocean Puzzle (Clue Puzzle)
- Heat Transfer and Cooling: Ocean Quick Fire (Quick Fire)
- Specific Heat and Calorimetry: Jungle Quick Fire (Quick Fire)
- Temperature, Heat and Expansion: Candy Puzzle (Clue Puzzle)
- Quiz: Change of State (8 questions)
- Quiz: Heat Transfer and Cooling (8 questions)
- Quiz: Specific Heat and Calorimetry (8 questions)
- Quiz: Temperature, Heat and Expansion (8 questions)