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Physics Chapters

9th Class Chapter 8 Physics Long Questions

Dear students, prepare for physics class 9th chapter 8 long questions. These important long questions are carefully added to get you best preparation for your 9th class physics ch. 8 exams.
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Question: 1
Q no 5<gwmw class="ginger-module-highlighter-mistake-type-6" id="gwmw-15862579562054743229825">(</gwmw>A) What is <gwmw class="ginger-module-highlighter-mistake-type-3" id="gwmw-15862579562051694198754">greenhouse effect</gwmw><gwmw class="ginger-module-highlighter-mistake-type-6" id="gwmw-15862579868369834462013">.</gwmw>Explain the impact of greenhouse it in to Celsius scale and Kelvin scale.
Answer: 1
1-22
Light from the sun contains thermal radiations of long wavelength as well as light and ultraviolet radiations of short wavelengthsglass and transparent polythenesheets allow radiations of short wavelength to pass through easily but not long wavelength of thermal radiations a green-housebecomes a heat trap. Radiations from the sun pass easily through glass and warms up the objects in a greenhouse. These objects in a greenhouse. These objects and plants such as give out radiations of much longer wavelength. Glass and transport poluthenesheets do not allow them to escapenot easily and are reflected back in the green houseGreen house effect promises betttergrowth of some plants.
Question: 2
Q no: 6<gwmw class="ginger-module-highlighter-mistake-type-6" id="gwmw-15862597205514709136289">(</gwmw>A) Explain land and Sea breeze are <gwmw class="ginger-module-highlighter-mistake-type-3" id="gwmw-15862597205516863643728">example</gwmw> of convection.?
Answer: 2
2-22
Land and Sea Breezes:
Land and Sea breezes are the result of convection.
Sea Breeze:
On a hot day the temperature of the land increase more quickly than the sea. itis because the specific heat of land is much smaller as compared to water. The air above land gets hot and rise up.
Land Breeze.
At night the land codsfasterthan the sea, therforeair above the sea is warmer, rise up and the cold air form the land begins to move towards the sea.

Question: 3
Q no: 7<gwmw class="ginger-module-highlighter-mistake-type-6" id="gwmw-15862613272305396402391">(</gwmw>A) What causes a glider to remain <gwmw class="ginger-module-highlighter-mistake-type-3" id="gwmw-15862613272303111206937">air</gwmw>.?
Answer: 3
3-22
A glider such looks like a small airoplanewithout engine. Glider pilots use of heat .These rising currents of hot air are called theimals, Gliders ride over these thermals, the upward movement of air currents in thermal helps them to stay in air for a long period.
The birds stretch out their wings and circle in these thermals, the upwordmovement of air help, birds toclimb up with it. Eagle hawks and vulture are expert thermal climber
Question: 4
Q no 6B) How much heat is required to charge10 g of water °C into of vaporization of water is 2.26 x 10<sup>6</sup> J kg-¹
Answer: 4
4-22
m= 100g = 0.1kg
t1 = 100° C
t2 = 100° C
Hu =2.26 x 106Jk-¹
φv = ?
Solution
φv= m x Hv
φv =0.1 x220 x106J
φv = 2.20 x 105J
Result
Heat required =φv=2.26 x 105J
Question: 5
Q no: 5 (B) How much heat is required to increase the temperature of 0.5 kg of water from 10°C to 65°C.?
Answer: 5
5-22
M= 0.5kg
T1= 10°C
T2=65°C
▲t=T2-T1
▲t = (65-10°c
▲t = 55°C
▲t = 55k
Required:
Φ=?
Solution:
▲Φ=mc▲T
▲Φ= 0.5 x 4200 x 55
▲Φ= 115500 J Ans

Question: 6
Q no: 7 (B) Normal temperature of is 98.6 F. Convert it in the Celsius scale and<gwmw class="ginger-module-highlighter-mistake-type-6" id="gwmw-15864247582428299949273"> .</gwmw>
Answer: 6
6-22
Solution:
Tf=98.6°F
Tk=?
c=5/9 (98.6-30)
c=5/9 (66.6)
c= 37°C
Tk=c +273
Tk =310k
Question: 7
Explain the temperature , heat , thermal equilibrium and internal energy
Answer: 7
7-22
Temperature: temperature of a body is the degree of hotness or coldness of the body
Question: 8
What is thermometer? explain it. write the thermometric properties of liquid
Answer: 8
8-22
Thermometer: a device that is used to measure the temperature of a body is called thermometer.
Question: 9
What is liquid-in-gas thermometer? explain it
Answer: 9
9-22
Liquid-in-gas thermometer; a liquid-in-gas thermometer has a bulb with a long capillary tube of uniform a nd fine bore. A suitable liquid is filled in the bulb. When the bulb contacts a hot object, the liquid in it expands and rises in the tube. The glass stem of a thermometer is thick and acts as a cylindrical lens. This makes it easy to see the liquid level in the glass tube.
Mercury freezes at -39C and boils at 357C. It has all the thermometric properties listed above. Thus mercury is one of the most suitable thermometric material. mercury-in glass thermometers are widely used in laboratories, clinics and houses to measure temperature in the range from -10C to 150C

Question: 10
Explain the scales of temperature
Answer: 10
10-22
Temperature scales: a scale is marked on thermometer. The temperature of the body in contact with the thermometer can be read on that scale.
Three scales of temperature are in common use. These are:
Question: 11
Define specific heat capacity. Give the importance of large heat capacity of water
Answer: 11
11-22
Specific heat capacity: specific heat capacity of a substance is defined as the amount of heat required to raise the temperature of 1kg mass of the substance through 1K.
Unit: the SI unit of specific heat capacity is JKg-1K-1
Examples: specific heat capacity of water , ice and soil are 4200 Jkg-1K-1, 2100Jkg-1k-1 and 810JKg-1K-1 respectively
Question: 12
Define and explain heat capacity
Answer: 12
12-22
Heat capacity: heat capacity of a body is the quantity of thermal energy absorbed by it for one kelvin(1K) increase in its temperature.
Question: 13
Define latent heat of fusion and explain it
Answer: 13
13-22
Latent heat of fusion: heat energy required to change unit mass of a substance from solid to liquid state at its melting point without change in its temperature is called its latent heat of fusion. It is denoted by Hf.
Ice changes at 0C into water. latent heat of fusion of ice is 3.36*105JKg-1. That is 3.36*105 joule heat is required to melt 1 kg of ice into water at 0C.
Question: 14
Define latent heat of vaporization. explain it
Answer: 14
14-22
Latent heat of vaporization: the quantity of heat that changes unit mass of a liquid completely into gas at its boiling point without any change in its temperature is caked latent heat of vaporization.
It is denoted by Hv.
When water is heated, it boils at 10C under standard pressure. its temperature remains 100C until it is changed completely into steam. Its latent heat of vaporization is 2.26*106JKg-1That is 1kg of water requires 2.26*106J heat to change it completely into gases at its boiling point.

Question: 15
Explain the change of state of matter
Answer: 15
15-22
Change of state of matter: Matter can be changed from one state to another. For such a change to occur, thermal energy is added to or removed from a substance
Question: 16
What is meant by evaporation: on what factors the evaporation of a liquid depends.
Answer: 16
16-22
Evaporation: evaporation is the changing of liquid into vapor's(gaseous state) from the surface of the liquid without heating it.
Question: 17
Write a note on linear thermal expansion in solids
Answer: 17
17-22
Thermal expansion; when heat is provided to any substances, the expansion of substances is known as thermal expansion.
Most of the substances solids, liquids and gases expand on heating and contract on cooling. Their thermal expansions and contractions are usually small and are not noticeable.
The kinetic energy of the molecule of an object depends on its temperature. The molecules of a solid vibrate with larger amplitude at high temperature than at low temperature.
Thus, on heating, the amplitude of vibration increase.
Thermal expansion results an increase in length, breadth and thickness of a substance.
Question: 18
Write a note on volume thermal expansion of solids
Answer: 18
18-22
Volume thermal expansion; the volume of a solid also changes with the change in temperature and is called volume thermal expansion or cubical thermal expansion
Question: 19
What is bimetal strip ? explain and write its uses
Answer: 19
19-22
Bimetal strip: a bimetal strip consists of two thin strips of different metals such as brass and iron joined together. On heating the strip , brass expands more than iron. This unequal expansion causes bending of strip.
Question: 20
Explain the consequences and application of thermal expansion.
Answer: 20
20-22
Consequences of thermal expansions: the expansion of solids may damage the bridge, railway tracks and roads as they are constantly subjected to temperature changes. So provision is made during construction for expansion and contraction with temperature. For example, railway tracks bucked on a hot summer day due to expansion if gaps are not left between sections.
Bridge made of steel girders also expands during the day and contract during night. They will bend if their ends are fixed. to allow thermal expansions, one end is fixed while the other end of the girder rests on rollers in the gap left for expansion. Overhead transmission lines are also given a certain amount of sag so that they can contract in winter without snapping.
Question: 21
Explain the consequences and also application of thermal expansion.
Answer: 21
21-22
Consequences of thermal expansions: the expansion of solids may damage the bridge, railway tracks and roads as they are constantly subjected to temperature changes. So provision is made during construction for expansion and contraction with temperature. For example, railway tracks bucked on a hot summer day due to expansion if gaps are not left between sections.
Bridge made of steel girders also expands during the day and contract during night. They will bend if their ends are fixed. to allow thermal expansions, one end is fixed while the other end of the girder rests on rollers in the gap left for expansion. Overhead transmission lines are also given a certain amount of sag so that they can contract in winter without snapping.
Question: 22
Briefly explain thermal expansion of liquids
Answer: 22
22-22
Thermal expansion of liquid: there molecules of liquids are free to move in all directions within the liquid. On heating a liquid, the average amplitude of vibration of its molecules increases. The molecule's push each other and need more space to occupy. This account for the expansion of the liquid when heated. The thermal expansion in liquids is greater than solids due to the weak forces between their molecules. Therefore, the coefficient of volume expansion of liquids is greater than solids. Liquids have no definite shape of their own. A liquid always attains shape of container in which it is pored. Therefore, when a liquid is heated, both liquid and the container