Heat and Temperature

5 min

Fundamental concepts, conversions, and thermal properties for competitive exams.

The Golden Rule of Thermal Physics

Heat flows spontaneously from high to low temperature. Specific heat causes temperature change, whereas latent heat changes the state of matter at a constant temperature.

Why this Topic is Crucial?

Direct numericals on Celsius to Fahrenheit conversion are very common in SSC and Railways.
Conceptual questions on the anomalous expansion of water (4°C) appear in almost every state exam.
Identifying modes of heat transfer (Conduction, Convection, Radiation) is a favorite for Police exams.

Quick Revision Hooks

Meet at Minus 40: Celsius and Fahrenheit scales are equal at -40°.
Four is Full: Water has maximum density at 4°C.
No Medium Sun: Radiation needs no medium to travel (like Sun's heat).

Temperature Scale Comparison

Scale	Freezing Pt.	Boiling Pt.
Celsius (°C)	0°C	100°C
Fahrenheit (°F)	32°F	212°F
Kelvin (K)	273.15 K	373.15 K

Heat Transfer & Water Property

Conduction

(Solid direct contact)

Solid direct contact

Heating a metal rod.

Convection

(Fluid particle movement)

Fluid particle movement

Boiling water in a pot.

Radiation

(Electromagnetic waves)

Electromagnetic waves

Sunlight reaching Earth.

4°C Density

(Anomalous expansion)

Anomalous expansion

Ice floats on water.

Exam Traps to Avoid

Latent heat increases temperature.Temperature remains constant.

During phase change (melting/boiling), temp does not rise until the process finishes.

Water expands when heated from 0 to 4.Water contracts from 0 to 4°C.

Water's volume decreases and density increases when heated from 0°C to 4°C.

Kelvin can be negative.Kelvin is never negative.

0 K is the lowest possible temperature (Absolute Zero).

Check Your Knowledge

Q1.What is the boiling point of water on the Fahrenheit scale?

Q2.By which method does heat from the Sun reach the Earth?

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