Install the general science textbook for class 7 in Punjabi in pdf format. a science textbook for students in grades 7 and 8. Soft copy of the entire book with vibrant printing. General science notes for grades 7 and 8 are both subjective and objective. Punjab Text Board has updated this book.
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General Science Book PTB: 7th Class
For your convenience, we have provided you with a list of textbooks for grades 7 and 8. Before you start reading, take a look at the following table of contents.
Organs of the human body
In humans as well as plants, transport
Relationships between Plants and Their Environment and Reproduction
The Atomic Water Structure
Changes and Processes in the Physical and Chemical Worlds
Sound Waves Dispersion of Light Heat Transmission
Electric and Circuit Diagrams Currently looking into the Index of Space Glossary
Bibliography
What's the use of using metal pots for cooking?
Because metals are good heat conductors, we use metal pots for cooking.
Defintion: What is convection?
A convection current is the movement of warm water upward and cold water downward.
Which surface is the most efficient at absorbing heat?
The dark surface is the most efficient in absorbing heat.
What's the use of wearing woollen clothing in the winter?
Ans: We wear and blankets made of natural wool in the fall and winter because they inhibit the transfer of heat.
Who benefits from the bird's ability to glide?
A bird's gliding flight saves a lot of energy because it doesn't have to flap its wings, but instead glides along with the wind currents.
Defintion: What is convection, exactly? What causes it?
Convection is the process by which molecules in a medium move toward and then away from a heat source in order to absorb heat.
Explain thermal energy.
In a nutshell, thermal energy refers to the energy of matter's motion.
What does thermal mean?
In a nutshell, thermal is a synonym for heat.
Do you know how hot things get?
A higher temperature object is cooled by a lower temperature object.
Give an example of heat transmission.
Ans: Heat transmission is the transfer of heat from one item to another.
How does heat go through the medium?
Ans; Solids, liquids, and gases.
How do solids hold their particles?
This is the case because of the tight packing of particles in solids.
What makes a conductor good?
The term "excellent conductors of heat" refers to materials that allow heat to easily flow through them.
What are some decent conductors?
Ans: Solids like metals are excellent heat conductors.
Do you know what constitutes a lousy conductor?
The term "poor conductors" refers to materials that restrict the transmission of heat through them.
Do you have any examples of poor conductors?
Wood, glass, and plastic are all poor heat conductors.
What is the best medium for transferring heat?
Answer: Mercury is an excellent heat conductor.
Refrigerators' interior walls are lined with what kind of insulating material?
Answer: The double walls of a refrigerator are separated by a layer of Styrofoam.
Examples of convection's influence.
Examples of convection include wind and ocean currents.
Radiation is a type of electromagnetic radiation.
Radiation is the term used to describe the direct passage of heat from a hot body to a cold body without heating the space in between.
What medium is necessary for the radiation of heat from the sun or heater?
Ans: There is no need for a middle.
Are good heat absorbents also good heat radiators?
Yes, a good heat absorber is also an excellent heat radiator.
Black or glossy, which surface is better at absorbing and radiating heat?
A good absorbing and warming surface is a black surface.
What is the purpose of the black paint on the refrigerator's back fins?
Because the back of freezers are painted black, they radiate heat.
What causes a vacuum in a vacuum flask to form?
It's a two-walled vacuum flask, correct? A vacuum is created by removing the air between the two walls.
It reduces the transfer of the heart by using a vacuum flask.
Answer: When a vacuum is present, heat transfer through conduction, convection, and radiation are all reduced.
Defintion of convection is required here.
In convection, molecules in a medium move toward the source of heat energy to absorb it, then move away from it to expel the heat that they have absorbed.
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