Download 7th Class General Science Notes (Unit-8) for Islamabad Model Schools & Colleges


SHORT QUESTIONS

State two differences between conduction and convection.
Conduction Convection
Heat travel through solids by conduction Heat travel through liquids by convection
Heat travel through atoms/molecules which are very close. Heat travel through actual movement of molecules.
List heat conducting material in your surroundings.
Silver, Copper, Aluminium, Brass, Iron etc. are good conductors of heat.
Why silver teapot is preferred to black teapot?
Silver teapot will not radiate heat quickly and thus remain hot for longer period.
What do we mean by convection?
Convection is the transfer of heat energy from one place to another by the movement of the substance itself.
Explain why cold water sinks when it is surrounded by warm water?
Cold water is heavier than warm water. That’s why cold water sinks when it is surrounded by warm water.
Explain why gases are poor conductors of heat?
Gases are very poor conductors of heat because their particles are widely separated so that collisions do not occur frequently to enable efficient energy transfer.
What do we mean by heat conductors?
Materials that conduct heat through them are called heat conductors. Silver, Copper, Aluminium, Brass, Iron etc. are good conductors of heat.

LONG QUESTIONS

Explain the differences between good and poor heat conductors. Give examples of each.
Good Conductors Poor Conductors
Heat can travel through them. Heat cannot travel through them.
Silver, Copper, Aluminium, Brass, Iron etc. are good conductors of heat. Vacuum, Air, Cork, Wood, Water, Glass etc. are poor conductors are heat.
How vacuum flask does maintain the temperature of the object inside it?
· Vacuum flask consists of two flasks, inserted one into the other and joined at the neck.
· The space between two flasks is evacuated vacuum, prevents heat transfer by conduction and convection.
· Heat transfer by radiation is reduced by silver coating flask surface with pure aluminum.
Explain the process of convection with the help of experiment.
· Take a beaker and fill it with water.
· Put some crystals of Potassium permanganate in it.
  • Heat up the beaker with burner.
· The warmer water expand, becomes less dense and rises making a trail of potassium permanganate.
What do you mean by conduction? Explain how heat is transferred through solids, particularly metals.
· The movement of heat through solid such as metals is called conduction.
· Take a metal bar and put some wax on its one end.
  • Heat other end.
  • After sometime wax start melting.
· This shows transfer of heat through bar by conduction.
What is meant by radiation? How will it be explained?
· Radiation is the transfer of heat energy through vacuum or any transparent media in the form of electromagnetic waves.
· For example heat of sun reaches us passing through space (vacuum).

7th Class General Science Notes for Islamabad Schools and Colleges

COMMENTS

Name

10th Class Notes,72,10th Class Old Papers,2,5th Class Notes,6,6th Class Notes,34,6th Class Old Papers,1,7th Class Notes,33,7th Class Old Papers,1,8th Class Notes,63,8th Class Old Papers,1,9th Class Notes,82,9th Class Old Papers,2,Articles,1,Download Free E-Books on IT,1,Home Tutors,3,Home Tutors in Islamabad & Rawalpindi,8,Home Tutors in Lahore,2,Home Tutors in Multan,1,Home Tutors in Wah Cantt & Taxila,3,Information Technology,1,Miscellaneous,10,News & Events,2,Notes & Handouts,292,Old Papers,8,Solved AIOU Assignments,1,Video Lectures,1,
ltr
item
Download Class Notes: Download 7th Class General Science Notes (Unit-8) for Islamabad Model Schools & Colleges
Download 7th Class General Science Notes (Unit-8) for Islamabad Model Schools & Colleges
Download 7th Class General Science Notes (Unit-8) for Islamabad Model Schools & Colleges
https://3.bp.blogspot.com/-8HrZ-9itVVk/V_fSEwgWJAI/AAAAAAAAC5w/9bV_XVoOeQIPB7948tbr1KsbwbASQJ1HQCLcB/s1600/7th_class_general_science_notes_islamabad.jpg
https://3.bp.blogspot.com/-8HrZ-9itVVk/V_fSEwgWJAI/AAAAAAAAC5w/9bV_XVoOeQIPB7948tbr1KsbwbASQJ1HQCLcB/s72-c/7th_class_general_science_notes_islamabad.jpg
Download Class Notes
http://www.downloadclassnotes.com/2016/11/unit-8-download-7th-class-vii-general-science-notes-for-islamabad-model-schools-colleges.html
http://www.downloadclassnotes.com/
http://www.downloadclassnotes.com/
http://www.downloadclassnotes.com/2016/11/unit-8-download-7th-class-vii-general-science-notes-for-islamabad-model-schools-colleges.html
true
6576910405746451012
UTF-8
Loaded All Posts Not found any posts VIEW ALL Readmore Reply Cancel reply Delete By Home PAGES POSTS View All RECOMMENDED FOR YOU LABEL ARCHIVE SEARCH ALL POSTS Not found any post match with your request Back Home Sunday Monday Tuesday Wednesday Thursday Friday Saturday Sun Mon Tue Wed Thu Fri Sat January February March April May June July August September October November December Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec just now 1 minute ago $$1$$ minutes ago 1 hour ago $$1$$ hours ago Yesterday $$1$$ days ago $$1$$ weeks ago more than 5 weeks ago Followers Follow THE DOWNLOAD LINK IS LOCKED Please share to unlock the download link Copy All Code Select All Code All codes were copied to your clipboard Can not copy the codes / texts, please press [CTRL]+[C] (or CMD+C with Mac) to copy