Heat

Heat – Class 7 Science Explained in Detail

Heat is a form of energy that causes things to become warmer. It plays a crucial role in our daily life—from cooking food and keeping warm in winter to industrial manufacturing and natural weather changes. Let’s dive deep into this fascinating topic.

What is Heat?

Heat is the energy transferred from one body to another due to the difference in temperature. It always flows from a hotter object to a colder one until both objects reach the same temperature.

Heat vs Temperature: Heat is energy, whereas temperature is a measure of how hot or cold an object is.

Measurement of Heat

The amount of heat is measured in units called joules (J). Another common unit used is the calorie.

Temperature and Its Measurement

Temperature is measured using a thermometer. There are different scales of temperature:

• Celsius (°C)
• Fahrenheit (°F)
• Kelvin (K)

Example: The normal human body temperature is 37°C or 98.6°F.

Thermometers

There are two main types of thermometers:

• Clinical Thermometer: Used to measure human body temperature. It has a kink to prevent the mercury from falling back on its own.
• Laboratory Thermometer: Used in labs to measure the temperature of various objects and substances.

Transfer of Heat

There are three main modes of heat transfer:

Mode	Description	Example
Conduction	Transfer of heat through a solid material from one particle to another.	Heating a metal rod
Convection	Transfer of heat in liquids and gases where warmer parts rise and cooler parts sink.	Boiling water
Radiation	Transfer of heat without any medium, through waves.	Sun warming the Earth

Conductors and Insulators

Materials that allow heat to pass through them are called conductors, e.g., metals like iron and copper. Materials that do not allow heat to pass through them easily are called insulators, e.g., wood, plastic, and rubber.

Practical Applications of Heat

• Cooking food using gas stoves or electric ovens
• Keeping homes warm using heaters in cold regions
• Ironing clothes
• Industrial welding and metal shaping

Example: Cooking rice on a gas stove involves conduction of heat from the flame to the vessel and then to the rice inside.

Precautions While Handling Heat

• Always use proper kitchen tools when handling hot utensils.
• Never touch electrical heaters or irons without protective gloves.
• Do not leave burning stoves unattended.

Conclusion

Heat is an essential part of our lives. Understanding how it works and how it is transferred helps us in various real-life applications—from science experiments to daily household tasks.

We hope this detailed explanation has helped you understand the concept of Heat better. Keep exploring, stay curious!