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Physics Chapters

9th Class Chapter 9 Physics Long Questions

Dear students, prepare for physics class 9th chapter 9 long questions. These important long questions are carefully added to get you best preparation for your 9th class physics ch. 9 exams.
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Question: 1
What is conduction. Explain it briefly
Answer: 1
1-13
Conduction in non-metals: non-metals are bad conductor of heat and the substances through which heat does not conduct are called bad conductors or insulators.Example: wood, cork, cotton, wool, glass, rubber, etc. are bad conductors or insulators.Conclusion: non-metals are insulators thus heat does not conduct through it.
Question: 2
What is thermal conductivity ? explain on which factors it depends
Answer: 2
2-13
Thermal conductivity: the rate of flow of heat across the opposite faces of a meter cube of a substance maintained at a temperature difference of one kelvin is called the thermal conductivity of that substance.
Unit: Wm-1K-1 is the unit of thermal conductivity.
Question: 3
what measures may b taken to save energy?
Answer: 3
3-13
In houses good thermal insulator means lower consumption of fuel.
Question: 4
Write the uses of conductors and non-conductors
Answer: 4
4-13
Uses of conductor: good conductors are used when quick transfer of heat is required through a body. Thus, cooker , cooking plates, boiler , radiators and condensers of refrigerators etc. are made 0f metals such or aluminum as copper . Similarly, metal box are used for making ice creams, etc..
Question: 5
Write the uses of conductors and non-conductors.
Answer: 5
5-13
Uses of conductor: good conductors are used when quick transfer of heat is required through a body. Thus, cooker , cooking plates, boiler , radiators and condensers of refrigerators etc. are made 0f metals such or aluminum as copper . Similarly, metal box are used for making ice creams, etc..
Question: 6
What is convection and convection currents in air? also write its uses
Answer: 6
6-13
Convection; transfer of heat by actual movement of molecules from hot place to a cold place is known as convection
Question: 7
What is sea an land breezes? also explain the gliding and their uses
Answer: 7
7-13
Sea breeze: on a hot day, the temperature of the land increases more quickly than the sea. It is because the specific heat of land is much smaller as compared to water. the air above land gets hot and rise up. Cold air from the sea begins to move towards the land as illustrated. It is called sea breeze.
Question: 8
What causes a glider to remain in air? describe
Answer: 8
8-13
Gliding: a glider looks like a a small aeroplane without engine. Glider pilots use upward movement of hot air currents due to convection of heat. these rising currents of hot air are called thermals.
Gliders ride over these thermals. The upward movement of air currents in thermals hep them to stay in air for a long period.
Question: 9
Define and explain the radiation<div>OR</div><div>How does heat reach us from sun?</div>
Answer: 9
9-13
Radiation: radiation is the mode of transfer of heat from one place to another in form of waves called electromagnetic waves. Radiation is that process of heat transfer in which heat energy reaches in the form of waves from one place to other without affecting the medium on its way.
Question: 10
What are the factors due to which radiation occurs
Answer: 10
10-13
Various factors such as:
  • Color and texture of the surface
  • Surface temperature
  • Surface area
Question: 11
Describe use of Leslie cube
Answer: 11
11-13
Leslie's cube: a Leslie cube is a meta box having forces of different nature and it used to identify the emission of radiation.
Question: 12
What is greenhouse ? also explain<div>t he greenhouse effect in global warming.</div>
Answer: 12
12-13
Greenhouse: a greenhouse is a heat trip. It is made of glass or transparent polythene sets that allow only radiations of short wavelength to pas through them. Radiation of long wavelength cannot enter or escape from green house.
Uses; greenhouse is usually used for plant growth
Question: 13
What are applications and consequences of radiation.
Answer: 13
13-13
Applications and consequences of radiation:
Absorption of heat: different objects absorb different amounts of heat radiations falling upon them reflecting the remaining part.
Dependence: the amount of heat absorb by a body depends upon the color and nature of its surface.
Example: a black and rough surface absorb more heat than a white or polished surface. Since good absorbers are also good radiators of heat. Thus, a black colored body gets hot quickly in summer by absorbing heat from its surrounding. It cools down quickly by giving out its heat to its surroundings. The bottom of cooking posts is made black to increase the absorption of heat from fire.