Asked/Added Questions From NCERT:

Question 1. Asked on :07 October 2020:05:43:48 PM

What happens if water vapour at a pressure of 0.004 atm is cooled to 0°C?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

nisha sheikh
if water vapour at a pressure of 0.003 atmosphere is cooled to 0^(@)C ... The pressure corresponding to triple point of water is 0.46 cm of Hg (=0.006 atm)

-Answered by nisha sheikh On 21 October 2020:06:51:15 PM

Question 2. Asked on :07 October 2020:05:40:35 PM

Are the relative amounts of ice, water and vapour fixed at the triple point of water?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva
At the triple point of water the temperature and pressure are fixed. However, the relative amounts of the three phases are not unique. The relative amounts o the three phases can be varied by adding or taking out heat from the system.

-Answered by Shruti Srivastva On 07 October 2020:05:41:45 PM

Question 3. Asked on :07 October 2020:05:37:14 PM

What is the significance of negative slope of ice line of water?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva
It indicates that the melting point if ice decreases with increase in pressure. This is because volume of water on melting is less than the volume of ice.

-Answered by Shruti Srivastva On 07 October 2020:05:38:53 PM

Question 4. Asked on :07 October 2020:05:35:26 PM

What is the temperature above which steam will not condense of water even i it is compressed to very large pressure?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva
Above the critical temperature steam will not condens.

-Answered by Shruti Srivastva On 07 October 2020:05:36:33 PM

Question 5. Asked on :07 October 2020:05:33:02 PM

How does the boiling point of water change with pressure?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva
The boiling point of water increaces with the increase in pressure.

-Answered by Shruti Srivastva On 07 October 2020:05:34:05 PM

Question 6. Asked on :07 October 2020:05:28:44 PM

What is the pressure on melting point of a solid?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva
The melting point o a soli may increase or decreaces depending on the nature of solid.

-Answered by Shruti Srivastva On 07 October 2020:05:31:57 PM

Question 7. Asked on :06 October 2020:06:07:27 PM

Can a gas be liquified at any temperature by the increase of pressure alone?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva
No.

-Answered by Shruti Srivastva On 06 October 2020:06:08:43 PM

Question 8. Asked on :06 October 2020:06:04:56 PM

What is critical temperature?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

nisha sheikh
The critical temperature of a substance is the temperature at and above which vapor of the substance cannot be liquefied, no matter how much pressure is applied. Every substance has a critical temperature.

-Answered by nisha sheikh On 07 October 2020:11:01:14 AM

Question 9. Asked on :06 October 2020:06:02:40 PM

In what respect is the respect is the thermal radiation different rom lights?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Anjali Kumari
Thermal radiation are electromagnetic waves having wavelength range from 700 nm to 1 mm. They produce heat when absorbed by a body. They are not visible

-Answered by Anjali Kumari On 09 October 2020:07:18:55 PM

Question 10. Asked on :06 October 2020:05:59:15 PM

Which object will cool faster when kept in open air, the one at 300°C or the one at 100°C?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva
300°C.

-Answered by Shruti Srivastva On 06 October 2020:06:02:04 PM

Question 11. Asked on :06 October 2020:05:58:18 PM

Black body radiation is white. Comment.

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

nisha sheikh
Black-body radiation has a characteristic, continuous frequency spectrum that depends only on the body's temperature, called the Planck spectrum or Planck's law. ... When the body appears white, it is emitting a substantial fraction of its energy as ultraviolet radiation

-Answered by nisha sheikh On 07 October 2020:11:03:27 AM

Question 12. Asked on :06 October 2020:05:56:05 PM

Why is there the word displacement in Wien's displacement law?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva
As the temperature is increased, the wavelength having maximum intensity is displaced towards the shoter wavelength region.

-Answered by Shruti Srivastva On 06 October 2020:05:56:56 PM

Question 13. Asked on :06 October 2020:05:52:16 PM

A hole in the cavity of a radiation is a black body. Why?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva

A hole in the cavity of a radiation does not reflect any radiation incident on it. So it is a black body.

-Answered by Shruti Srivastva On 06 October 2020:05:54:54 PM

Question 14. Asked on :06 October 2020:05:51:00 PM

Why are clear nights colder then cloudy nights?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

nisha sheikh
This is true even during complete overcast conditions because the clouds are generally colder than the air at the ground. Thus clouds in effect reduce the radiation imbalance between the upward flux from the ground and downward flux from the atmosphere, relative to that on clear nights.

-Answered by nisha sheikh On 07 October 2020:11:04:30 AM

Question 15. Asked on :06 October 2020:05:48:39 PM

Is it necessary that all black coloured objects should be considered black bodies?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva
No.

-Answered by Shruti Srivastva On 06 October 2020:05:49:47 PM

Question 16. Asked on :06 October 2020:05:46:01 PM

Why does a piece o red glass absorbs green colour strongly. But at higher temperatures, it emits green colour strongly.

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva
At low temperatures, the red glass absorbs green colour strongly. But at higher temperatures, it emits green colour strongly.

-Answered by Shruti Srivastva On 06 October 2020:05:47:52 PM

Question 17. Asked on :06 October 2020:05:43:35 PM

Why a body with large reflectively is a poor emitter?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva
A body whose reflectively is large would naturally absorb less heat. So, a body with large reflectively is a poor emitter.

-Answered by Shruti Srivastva On 06 October 2020:05:44:30 PM

Question 18. Asked on :06 October 2020:05:42:13 PM

Why do animals curl 8 into a ball, when they feel very cold?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

nisha sheikh

Animals curl up into a ball when they're feeling cold in order to minimize the heat loss. The heat from the body of animal will flow towards the cold.

-Answered by nisha sheikh On 07 October 2020:11:06:30 AM

Question 19. Asked on :06 October 2020:05:39:28 PM

Why are the cooling coils fitted near the ceiling of a refrigerator?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva
As the air gets cooled in the upper part o refrigerator, it becomes denser and goes down.

-Answered by Shruti Srivastva On 06 October 2020:05:41:06 PM

Question 20. Asked on :06 October 2020:05:37:27 PM

Water is heated from below. why?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva
When water is heated, its density decreases and it rise up.

-Answered by Shruti Srivastva On 06 October 2020:05:38:13 PM

Question 21. Asked on :06 October 2020:05:34:19 PM

Why snow is a better heat insulator than ice?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

nisha sheikh
Snow is better insulator than ice because snow contains air packets inside it and air is a good insulator of heat . Due to this , snow takes longer time to melt than ice of same mass .

-Answered by nisha sheikh On 07 October 2020:11:07:14 AM

Question 22. Asked on :03 October 2020:06:04:38 PM

Why it is much hotter above a fire than by its side?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva

Heat carried away from a fire sideways mainly by radiation. Above the fire, heat is carried by both radiation and convection of air.

-Answered by Shruti Srivastva On 06 October 2020:05:32:45 PM

Question 23. Asked on :03 October 2020:06:03:36 PM

Why rooms are provided with the ventilators near the roof?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva
To purify air.

-Answered by Shruti Srivastva On 03 October 2020:06:04:21 PM

Question 24. Asked on :03 October 2020:06:00:55 PM

Why small holes are provided at the bottom of the chimney of the lamp?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva
The hot air and burnt gases rise upwards through the chimney. Fresh air enters through the holes provided at bottom. In the absence of these holes, convection currents will not be set up and the lamp would go off.

-Answered by Shruti Srivastva On 03 October 2020:06:01:43 PM

Question 25. Asked on :03 October 2020:05:58:43 PM

I air is poor conductor of heat, why do we not feel warm without clothes?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva
Althrough air is poor conductor of heat, it carries away heat from body due to convection when we are without clothes. Hence we feel cold.

-Answered by Shruti Srivastva On 03 October 2020:05:59:41 PM

Question 26. Asked on :03 October 2020:05:55:03 PM

Why felt rather than air is employed for thermal insulation?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva
Through air is a bad conductor of it, it transfers heat easily by convection. Felt traps air between its fibres and convection currents cannot be set up in it.

-Answered by Shruti Srivastva On 03 October 2020:05:56:08 PM

Question 27. Asked on :03 October 2020:05:52:19 PM

Why do elctrons in insulator or not contribute towards its thermal conductivity?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva
Electrons do not have free electrons inside them. So electrons have no contibution towards their thermal conductivity.

-Answered by Shruti Srivastva On 03 October 2020:05:53:30 PM

Question 28. Asked on :03 October 2020:05:49:14 PM

Usually a good conductor of heat is a good conductor of elcectricity also. Give reason?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva
Electron contribute largerly both towards the flow of elctricity and the flow of heat. A good conductor cntains a large number of free electrons. So it is both a good conductor o heat and elctricity.

-Answered by Shruti Srivastva On 03 October 2020:05:50:18 PM

Question 29. Asked on :03 October 2020:05:46:42 PM

Stainless steel cooking pans are perferrred with extra copper bottom. Why?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva
The thermal conductivity of copper is much larger than that of steel.The copper bottom allows more heat of flow into the pan and hence help in cooking the food faster.

-Answered by Shruti Srivastva On 03 October 2020:05:47:45 PM

Question 30. Asked on :03 October 2020:05:45:43 PM

Why do we use copper gauze in davy's afety lamp?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Anjali Kumari
The final design was very simple: a basic lamp with a wire gauze chimney enclosing the flame. The holes let light pass through, but the metal of the gauze absorbs the heat. The lamp is safe to use because the flame can't heat enough flammable gas to cause an explosion, although the flame itself will change colour.

-Answered by Anjali Kumari On 11 October 2020:02:12:35 PM

Question 31. Asked on :03 October 2020:05:43:15 PM

Woole clthes are warm in winter. Why?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva
Woolen fibres enclos a large amount of air in them. Both wool and air are bad conductor of heat. The small coefficient of thermal conductivity prevets the loss of heat from our body due to conduction. S o we feel warm in woolen clothes.

-Answered by Shruti Srivastva On 03 October 2020:05:43:54 PM

Question 32. Asked on :03 October 2020:05:41:08 PM

A piece of wire gauze is placed over the Bunsen burner. If the gas is turned on below the gauge, will the flame go above the gauge?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva
Copper is a very good conductor o heat. The copper gauze absorbs most o the heat.

-Answered by Shruti Srivastva On 03 October 2020:05:42:30 PM

Question 33. Asked on :03 October 2020:05:37:55 PM

Why we can easily boil water in a paper cup?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva
This is because heat is easily conducted through the paper to the water, and as such the temperature through the paper to the water, and as such the temperature attained is not sufficient for the paperto be charred.

-Answered by Shruti Srivastva On 03 October 2020:05:38:44 PM

Question 34. Asked on :03 October 2020:05:35:08 PM

When we step barefoot into an ofice with a marble floo, we feel cold. Why?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva
This is because marble is a better conductor of heat than concrete. When we walk barefooted on a marble floor, heat flows our body through the feet and we feel cold.

-Answered by Shruti Srivastva On 03 October 2020:05:36:00 PM

Question 35. Asked on :03 October 2020:05:33:33 PM

Calorimeters are made of metals not glass.Why?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva
This is because metals are good conductors of heat and have low specific heat capacity.

-Answered by Shruti Srivastva On 03 October 2020:05:34:19 PM

Question 36. Asked on :03 October 2020:05:31:13 PM

A squirrel wraps its bushy tail round its body during its winter sleep.Why?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva
The bushy tail provides its body a non-conducting blankets. So the loss of heat by conduction is minimised.

-Answered by Shruti Srivastva On 03 October 2020:05:32:27 PM

Question 37. Asked on :03 October 2020:05:28:37 PM

Why are two thin blankets are warmer then a single blanket of double the thickness?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva
The air enclosed between two blankets prevents the transfer o heat from our body to outside.

-Answered by Shruti Srivastva On 03 October 2020:05:29:33 PM

Question 38. Asked on :03 October 2020:05:26:18 PM

Why an ice box is constructed with a double wall?

-Added by Shruti Srivastva Chemistry » Thermal Properties Of Matter

Answer:

Shruti Srivastva
An ice box is made of double wall and the space between the walls is filled with some non-conducting material to provide heat insulators, so that the loss of heat can be minimised.

-Answered by Shruti Srivastva On 03 October 2020:05:27:03 PM

Question 39. Asked on :03 October 2020:05:24:34 PM

Why birds are often seen to swell their feathers in winter?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva
When the birds swell there fether, they are able to enclose air in the feathers.

-Answered by Shruti Srivastva On 03 October 2020:05:25:25 PM

Question 40. Asked on :02 October 2020:06:28:37 PM

Why do metal utensils have wooden handles?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva
Because wood is a bad conductor of heat.

-Answered by Shruti Srivastva On 02 October 2020:06:29:20 PM

Question 41. Asked on :02 October 2020:06:25:57 PM

What kind of thermal conductivity and specific heat requirments would you specify for cooking utensils?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva
A cooking utensils should have high conductivity so that it can conduct heat through itself and transfer it to the contents quickly.

-Answered by Shruti Srivastva On 02 October 2020:06:27:12 PM

Question 42. Asked on :02 October 2020:06:24:08 PM

Why is water used as an eective coolant?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva
The specific heat of water is very high. When it runs over hot parts of an engine or machinery, it absorbs a large amount of heat.

-Answered by Shruti Srivastva On 02 October 2020:06:24:46 PM

Question 43. Asked on :02 October 2020:06:22:40 PM

Why juice bottles are placed under water in the cold countries?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva
This is done so to prevent the freezing of juice.

-Answered by Shruti Srivastva On 02 October 2020:06:23:33 PM

Question 44. Asked on :02 October 2020:06:20:48 PM

Why water is preffered to any other liquid in the hot water bottles?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva

water is preffered to any other liquid in the hot water bottles because due to high specific heat is does not cool fast. Also for the given mass of water.

-Answered by Shruti Srivastva On 02 October 2020:06:21:37 PM

Question 45. Asked on :02 October 2020:06:18:38 PM

What is the differences between the specific heat and the molar specific heat?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva
The specific heat is the heat capacity per unit mass whereas the molar specific heat is the heat capacity per mole.

-Answered by Shruti Srivastva On 02 October 2020:06:19:35 PM

Question 46. Asked on :02 October 2020:06:15:38 PM

Give an example of a system in which no heat s transferred to or from a system but the temperature of the system changes.

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva
When a paddle wheel arrangement is worked while dipping in water, the temperature of water increaces without any addition of heat.

-Answered by Shruti Srivastva On 02 October 2020:06:17:21 PM

Question 47. Asked on :02 October 2020:06:13:04 PM

If an elctric fan be switched in a closed room, will the air of the room be cooled? If not, why do we feel cold?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva
The air will not be cooled. In fact, it will get heated up due to the increase in the speed o its molecules. we feel cold due to faster evaporation of sweat.

-Answered by Shruti Srivastva On 02 October 2020:06:14:18 PM

Question 48. Asked on :02 October 2020:06:10:46 PM

A match stick can be lighted by rubbing it against a rough surface. Why?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva
When the match stick is rubbed against a rough surace , work is done against friction. This work done appears as heat and lights up the match stick.

-Answered by Shruti Srivastva On 02 October 2020:06:11:51 PM

Question 49. Asked on :02 October 2020:06:09:45 PM

Can a given amount of mechanical energy be completely converted into heat?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva
Yes.

-Answered by Shruti Srivastva On 02 October 2020:06:10:35 PM

Question 50. Asked on :02 October 2020:06:05:32 PM

Why do the brake drums of a car get heated, when the car moves down a hill at a constant speed?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva
As the car moves down a hill at constant speed, its kinetic energy does not change. But its gravitational potential energy constantly decreaces, which gets converted into heat and so the brake drums get heated.

-Answered by Shruti Srivastva On 02 October 2020:06:06:28 PM

Question 51. Asked on :02 October 2020:06:02:25 PM

There is a slight temperature differnces between the water all at the top and the bottom. Why?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva
The potential energy of water at the top of the fall gets converted into heat kinetic energy at the bottom of the fall. When water hite=s the ground, a part of its kinetic energy gets converted into heat which increaces its temperature slightly.

-Answered by Shruti Srivastva On 02 October 2020:06:03:23 PM

Question 52. Asked on :02 October 2020:05:59:10 PM

When we rub oue hands, they are warmed but only to a certain maximum temperature. Why?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva
The work done in rubbing is converted into heat. But ater some time when the temperature of the hand is raised, the total heat produced goes into the atmosphere.

-Answered by Shruti Srivastva On 02 October 2020:06:00:39 PM

Question 53. Asked on :02 October 2020:05:56:38 PM

A thermous bottle containing water is vigorously shaken. What will be theeffect on the temperature of water?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva
The temperature of the water will increaces slightly. This is because some o the work done against opposing viscous force will be converted into heat.

-Answered by Shruti Srivastva On 02 October 2020:05:57:52 PM

Question 54. Asked on :02 October 2020:05:54:43 PM

Why is J called a converter factor?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva
Because it help us to convert work measured in terms of joules into heat expressed in calories or vice-versa.

-Answered by Shruti Srivastva On 02 October 2020:05:55:23 PM

Question 55. Asked on :02 October 2020:05:53:38 PM

Is J a physical quantity?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva
No.

-Answered by Shruti Srivastva On 02 October 2020:05:54:21 PM

Question 56. Asked on :02 October 2020:05:49:32 PM

Explain why a beaker filled with water a 4ºC overflows if the temperarure is decreased or increased?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva
It is because of the anamalous expansion o water. Water has a maximum density at 4°C. Therefore, water expands wheter it is heated above 4°C or cooled below 4°C.

-Answered by Shruti Srivastva On 02 October 2020:05:51:20 PM

Question 57. Asked on :02 October 2020:05:46:39 PM

How does the diameter of the opening in the cast iron plate of a kitchen stove change, when the stove is heated?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva
The opening in the stove is circular. But its diameter undergoes linear expansion on heating.

-Answered by Shruti Srivastva On 02 October 2020:05:48:17 PM

Question 58. Asked on :30 September 2020:06:17:30 PM

In riveting boiler plates, red hot riverts are used. Why?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva
Red hot revets are used so that on cooling, the grip becomes firm and steam tight.

-Answered by Shruti Srivastva On 30 September 2020:06:18:23 PM

Question 59. Asked on :30 September 2020:06:16:32 PM

Why iron rims are heated red hot before being put on the cart wheels?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Anjali Kumari
The iron ring to be put on the rim of a cart wheel is always of slightly smaller diameter than that of the wheel. When the iron ring is heated to become red hot, it expands and slips on to the wheel easily. When it is cooled, it contracts and grips the wheel firmly.

-Answered by Anjali Kumari On 11 October 2020:02:07:50 PM

Question 60. Asked on :30 September 2020:06:14:26 PM

Thick bottomed drinking glasses frequently crack if hot water poured into them. Why?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva
Glass is bad conductor of heat. It does not pass down the heat quickly to the lower surface.

-Answered by Shruti Srivastva On 30 September 2020:06:15:36 PM

Question 61. Asked on :30 September 2020:06:12:19 PM

A tightened glass stopper can be taken out easily by pouring hot water around the neck o the bottle. Why?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva
The neck expands but not the stopper due to poor conductivity of glass. Thus the stopper can be taken out easily.

-Answered by Shruti Srivastva On 30 September 2020:06:13:27 PM

Question 62. Asked on :30 September 2020:06:09:37 PM

A brass disc fits snugly in a hole in a steel plate. Should we heat or cool the system to loosen the disc from the hole?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva
a brass is greter than that or steel. On cooling, the disc shrinks to a grater extent than the hole, and hence the disc would get loosened.

-Answered by Shruti Srivastva On 30 September 2020:06:11:06 PM

Question 63. Asked on :30 September 2020:06:07:05 PM

Why must telephone or power lines necessarily slag a little?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva
This slag is allow for contradiction in winter. If no sag is allowed, the wire may snap in extremely cold weather.

-Answered by Shruti Srivastva On 30 September 2020:06:08:09 PM

Question 64. Asked on :30 September 2020:06:04:35 PM

Why are loops provided in long metal pipes used for cappying oil and any other liquid over long distances?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva
The loops in metal pipes are provided in order to avoid the strain that would develop in the pipes when the temperature changes and hence the pressure of liquids in them changes.

-Answered by Shruti Srivastva On 30 September 2020:06:05:44 PM

Question 65. Asked on :30 September 2020:06:02:41 PM

Why a small gap is left between the iron rails of railway tracks?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva
If no gap is let between the iron rails, the rails may bend due to expansion in summer and the train may get derailed.

-Answered by Shruti Srivastva On 30 September 2020:06:03:32 PM

Question 66. Asked on :30 September 2020:06:01:42 PM

Is the temperature coeficient always positive?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva
No.

-Answered by Shruti Srivastva On 30 September 2020:06:02:24 PM

Question 67. Asked on :30 September 2020:05:59:18 PM

Why does a solid expand on heating?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva
The average distance between the positions of equillibrium of the atoms of a solid increaces with an increase in temperature which results in the thermal expansion of a solid.

-Answered by Shruti Srivastva On 30 September 2020:06:00:05 PM

Question 68. Asked on :30 September 2020:05:57:34 PM

Do all solids expand on hetaing?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva
No.

-Answered by Shruti Srivastva On 30 September 2020:05:59:02 PM

Question 69. Asked on :30 September 2020:05:55:32 PM

A body at higher temperature contains moer heat, comment.

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva
The statement is not always true.The heat content of a body depends upon its mass, specific heat and temperature.

-Answered by Shruti Srivastva On 30 September 2020:05:56:22 PM

Question 70. Asked on :30 September 2020:05:52:41 PM

Why is a constant volume gas thermometer preffered as a standard thermometer than a constant pressure gas thermometer?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva
This is because the changes in pressure can be measured with greater accuracy than changes in volume.

-Answered by Shruti Srivastva On 30 September 2020:05:54:27 PM

Question 71. Asked on :30 September 2020:05:50:27 PM

Why the temperature above 1200ºC cannot be measured accurately by a platinum resistance thermometer?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva
This is because platinum begins to evaporation above 1200ºC.

-Answered by Shruti Srivastva On 30 September 2020:05:51:45 PM

Question 72. Asked on :30 September 2020:05:46:54 PM

Mercury boils at 357ºC. How can then a mercury thermometer be used to measure temperature upto 500ºC?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva
The space above the mercury is filled with nitrogen. This increaces the boling point of mercury and raises the upper limit of the mercury thermometer.

-Answered by Shruti Srivastva On 30 September 2020:05:48:42 PM

Question 73. Asked on :30 September 2020:05:45:40 PM

Can the temperature of a body be negative on the kelvin scale?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva

No.

-Answered by Shruti Srivastva On 30 September 2020:05:46:31 PM

Question 74. Asked on :30 September 2020:05:43:53 PM

Why are gas thermometers are more sensitive than mercury thermometers?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva
The coefficient of expansion of a gas is very large as compared to the coeicient of expansion o mercury.

-Answered by Shruti Srivastva On 30 September 2020:05:44:36 PM

Question 75. Asked on :30 September 2020:05:41:44 PM

What do you mean by triple point of water? Why it is unique?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva
It is the temperature at which the three phases of water: ice, liquid, and water vapour are equally stable and exsist simultaneously.

-Answered by Shruti Srivastva On 30 September 2020:05:42:38 PM

Question 76. Asked on :30 September 2020:05:38:33 PM

Why should a thermometer bulb have a small heat capacity?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva
Because it absorb less heat from the body whose temperature s to be measured. Hence the temperature of that body will practically unchanged.

-Answered by Shruti Srivastva On 30 September 2020:05:40:14 PM

Question 77. Asked on :26 September 2020:06:11:42 PM

Why a clinical thermometer should not be sterilized by boiling?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva
The range of clinical thermometer is usually from 95º to 110ºF and the boiling point of water is 212º .

-Answered by Shruti Srivastva On 26 September 2020:06:12:56 PM

Question 78. Asked on :26 September 2020:06:08:59 PM

What is dynamical theory of water?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva
According to dynamical theory, the amount of heat possessed by a body is equal to the total kinetic energy o ots molecules and its temperature is proportional to the average kinetic energy of its molecules.

-Answered by Shruti Srivastva On 26 September 2020:06:09:50 PM

Question 79. Asked on :26 September 2020:06:07:06 PM

Is temperature a macroscopic or microscopic concept?

-Added by Shruti Srivastva Physics » Thermal Properties Of Matter

Answer:

Shruti Srivastva
Temperatue is macroscopic concept.

-Answered by Shruti Srivastva On 26 September 2020:06:08:24 PM

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