Key relationship
Q=Pt; sensible Q=mcΔT; phase change Q=mL (Lfusion=334 kJ/kg, Lvapor=2256 kJ/kg).
Physics · Class 11
Heat ice through state changes
During melting or boiling, heat changes the state while temperature stays constant. Between state changes, heat increases temperature according to the relevant specific heat. The horizontal plateaus represent energy, not a failed heater.
Open the interactive experiment →Heat ice through state changes
உருகல் மற்றும் கொதித்தலில் வெப்பம் நிலை மாற்றத்திற்குப் பயன்படும்; வெப்பநிலை மாறாது. நிலை மாற்றம் முடிந்த பிறகே வெப்பநிலை உயர்கிறது.
Key notes, relationships and model limits
Remember
During melting or boiling, heat changes the state while temperature stays constant. Between state changes, heat increases temperature according to the relevant specific heat. The horizontal plateaus represent energy, not a failed heater.
Common trap
Heat input does not always increase temperature.
Model limits
Ice starts at −10°C at 1 atm; fixed mass, ideal lossless heating, constant heat capacities. Melting and boiling remain at 0°C and 100°C until each latent stage is complete.
What you will learn
Interpret heating-curve slopes and latent-heat plateaus.
Try the experiment
Try both scenarios, change one control, and predict the result before checking the graph and readouts.
Think of it this way
Change one input while keeping the others fixed, as you would in a controlled experiment.
Worked example
Warming 0.05 kg ice from −10°C to 0°C needs 1050 J. With 500 W, melting finishes after (1050+16700)/500=35.5 s.
Why this matters
The model connects heat ice through state changes with an observable reading. Check the equation and assumptions before applying it.
Before you start
SI units · algebra · graph reading
Check your understanding
How much heat melts 0.05 kg of ice already at 0°C?
- 1050 J
- 16700 J
- 334000 J
Read the explanation
Q=mLf=0.05×334000=16700 J.
Course connection: Class XI Chapter 10. Consult the roadmap for CBSE, NEET, JEE Main and Advanced scope.