PPT: Heat Transfer in Nature | PPTs for Class 7 PDF Download

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Heat Transfer in Nature
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Heat Transfer in Nature
Conduction of Heat
What is Conduction?
Conduction is the process by which heat is 
transferred from the hotter part of an object 
to its colder part through direct contact. In 
solids, especially metals, particles vibrate 
when heated and pass this energy to 
neighboring particles without moving from 
their positions. This makes conduction an 
important process in everyday activities like 
cooking.
How Conduction Works
When one end of a metal object is heated, the 
particles at that end gain energy and vibrate 
more. These vibrations are passed to 
adjacent particles, transferring heat along the 
object. For example, when a metal pan is 
heated, the heat travels from the flame to the 
entire pan, making it hot.
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Heat Transfer in Nature
Conduction of Heat
What is Conduction?
Conduction is the process by which heat is 
transferred from the hotter part of an object 
to its colder part through direct contact. In 
solids, especially metals, particles vibrate 
when heated and pass this energy to 
neighboring particles without moving from 
their positions. This makes conduction an 
important process in everyday activities like 
cooking.
How Conduction Works
When one end of a metal object is heated, the 
particles at that end gain energy and vibrate 
more. These vibrations are passed to 
adjacent particles, transferring heat along the 
object. For example, when a metal pan is 
heated, the heat travels from the flame to the 
entire pan, making it hot.
Conduction Activity
Materials Needed
Metal strip (aluminium or iron)
Four pins
Candle or spirit lamp
Stand (or two bricks for support)
Wax to attach the pins
Heat source
Steps
Take a metal strip (15 cm long) and 
attach four pins to it using wax, spaced 
about 2 cm apart.
1.
Secure the strip to a stand or between 
two bricks.
2.
Heat the end of the strip away from the 
stand with a candle or spirit lamp.
3.
Observe and predict the behavior of 
the pins.
4.
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Heat Transfer in Nature
Conduction of Heat
What is Conduction?
Conduction is the process by which heat is 
transferred from the hotter part of an object 
to its colder part through direct contact. In 
solids, especially metals, particles vibrate 
when heated and pass this energy to 
neighboring particles without moving from 
their positions. This makes conduction an 
important process in everyday activities like 
cooking.
How Conduction Works
When one end of a metal object is heated, the 
particles at that end gain energy and vibrate 
more. These vibrations are passed to 
adjacent particles, transferring heat along the 
object. For example, when a metal pan is 
heated, the heat travels from the flame to the 
entire pan, making it hot.
Conduction Activity
Materials Needed
Metal strip (aluminium or iron)
Four pins
Candle or spirit lamp
Stand (or two bricks for support)
Wax to attach the pins
Heat source
Steps
Take a metal strip (15 cm long) and 
attach four pins to it using wax, spaced 
about 2 cm apart.
1.
Secure the strip to a stand or between 
two bricks.
2.
Heat the end of the strip away from the 
stand with a candle or spirit lamp.
3.
Observe and predict the behavior of 
the pins.
4.
Conduction Activity Results
Prediction
You are asked to predict the order in 
which the pins will fall as the strip is 
heated.
Observation
The first pin (Pin I), closest to the 
candle flame, falls first, followed by 
the other pins in order (II, III, and IV). 
The reason for the sequential fall of 
the pins is the process of heat 
conduction.
Explanation
Conduction is the process of heat 
transfer from the hotter part of a 
material to the cooler part. As the heat 
travels along the metal strip, it causes 
the wax holding each pin to melt, 
leading to the pin falling. The heat is 
transferred from the hot end (near the 
flame) to the colder end through the 
metal particles vibrating and passing 
on the energy to their neighbours. 
Metals are good conductors of heat, 
which is why metal utensils are used 
for cooking.
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Heat Transfer in Nature
Conduction of Heat
What is Conduction?
Conduction is the process by which heat is 
transferred from the hotter part of an object 
to its colder part through direct contact. In 
solids, especially metals, particles vibrate 
when heated and pass this energy to 
neighboring particles without moving from 
their positions. This makes conduction an 
important process in everyday activities like 
cooking.
How Conduction Works
When one end of a metal object is heated, the 
particles at that end gain energy and vibrate 
more. These vibrations are passed to 
adjacent particles, transferring heat along the 
object. For example, when a metal pan is 
heated, the heat travels from the flame to the 
entire pan, making it hot.
Conduction Activity
Materials Needed
Metal strip (aluminium or iron)
Four pins
Candle or spirit lamp
Stand (or two bricks for support)
Wax to attach the pins
Heat source
Steps
Take a metal strip (15 cm long) and 
attach four pins to it using wax, spaced 
about 2 cm apart.
1.
Secure the strip to a stand or between 
two bricks.
2.
Heat the end of the strip away from the 
stand with a candle or spirit lamp.
3.
Observe and predict the behavior of 
the pins.
4.
Conduction Activity Results
Prediction
You are asked to predict the order in 
which the pins will fall as the strip is 
heated.
Observation
The first pin (Pin I), closest to the 
candle flame, falls first, followed by 
the other pins in order (II, III, and IV). 
The reason for the sequential fall of 
the pins is the process of heat 
conduction.
Explanation
Conduction is the process of heat 
transfer from the hotter part of a 
material to the cooler part. As the heat 
travels along the metal strip, it causes 
the wax holding each pin to melt, 
leading to the pin falling. The heat is 
transferred from the hot end (near the 
flame) to the colder end through the 
metal particles vibrating and passing 
on the energy to their neighbours. 
Metals are good conductors of heat, 
which is why metal utensils are used 
for cooking.
Conductors and Insulators of Heat
Good Conductors of Heat
Metals (e.g., aluminium, iron) allow heat to pass 
through them easily.
This is why metal cooking utensils are commonly 
used.
Poor Conductors of Heat (Insulators)
Materials like wood, glass, clay, and porcelain do 
not allow heat to pass through easily. For example:
Tea or coffee cups made of clay or porcelain 
help in retaining heat longer.
Woollen fabrics trap air, which is a poor 
conductor, and help keep us warm.
The presence of air between layers of clothing 
(such as woolen clothes or blankets) reduces heat 
flow and helps keep us warm. Air trapped between 
two thin blankets acts as an insulator