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Heat lost by the hot body is equal to the heat gained by the cold body.

(a) temperature

(b) clinical

(c) Celsius

(d) radiation

(e) conduction

(J) dark

Conductors – aluminium, iron

Insulators – plastic, wood.

The materials which do not allow heat to pass through them easily are poor conductors of heat. 

Ex: Water, air, clothes, glass, cork, plastic, wood etc. They are also known as insulators.

Conductors : copper, aluminium and iron. 

Insulators : wood and plastic.

The air gets trapped between two layers of warm clothes. Air acts as insulator of heat. This layer prevents our body heat to escape in the surroundings. More layers of thin clothes will allow more air to get trapped and as a result we will not feel cold. So wearing more layers of clothing during winter keeps us warmer than wearing just one thick piece of clothing.

Conductors: Copper, aluminum and iron. Insulators: Wood, water and air.

Depending on thermal conductivity materials are of two types : 

They are 

1. Good conductors 

2. Poor conductors (insulators}.

The ability of a material to conduct heat is called thermal conductivity.

Kelvin : Kelvin is written as K and read as Kelvin.

The normal temperature of the human body is 37°C or 98.4°F.

Degree Celsius : Celsius is written as °C and read as degree Celsius. Celsius is also called Centigrade.

Degree Celsius : Temperature is measured in Degree Celsius (°C).

Degree Fahrenheit : Fahrenheit i$ written as °F and read as degree Fahrenheit.

The abnormal variation in the components of climate is called climate change.

Smoke and hot air moves up because it expands and becomes lighter.

The force applied by air on any surface in contact is called “air pressure”.

The average weather pattern taken over a long period is called the climate of the place.

The variations of hotness, coldness can be termed as degree of hotness and coldness.

Quilts are filled with fluffy cotton. Air is trapped in the fine pores of cotton. Cotton and air are the insulators of heat. They check heat from our body to escape and thus keep us warm. 

The newly made quilts are warmer than the old ones because in the old quilts, there is no air trapped in the cotton.

By the process of convection, heat is always transferred vertically upwards. The reason is that the medium particles near the source of heat absorb heat from the source and they start moving faster. As a result, the medium at this place becomes less dense so it rises up and the medium from above being denser, moves down to take its place. Thus, current is set up in the medium which is called a convection current. The current continues till the entire medium acquires the same temperature.

Ventilators and windows are provided in rooms for proper ventilation. The reason is that when we breathe out in a room, the air in the room becomes warm and impure. The warm air is less dense i.e. lighter, so it rises up and moves out through the ventilators. Then the cold fresh air comes in the room through the windows to take its place. Thus the continuous circulation of fresh air keeps the air in the room fresh.

Chimneys are provided over the furnace in factories. This is because the hot gases coming out of the furnace are less dense than the air. They rise up through the chimney. The smoke, fumes etc. around the furnace rush in so as to take their place and they are sucked out. Thus, the chimney helps to remove the undesired fumes, smoke etc. from the premises.

Similarities: 

1. Working principle of both the thermometer is same. 

2. Both are used to measure temperature. 

3. Mercury is used in both thermometers to measure temperature. 

4. Both have Celsius and fahrenheit markings. 

5. Both have a bulb at one end.

Differences : 

1. Laboratory thermometer is used to measure temperature of different objects in factories and laboratory where as clinical thermometer is used to measure the temperature of human beings only. 

2. Laboratory thermometer has temperature range from -10°C to 110°C where as clinical thermometer has temperature range from 35°C to 42°C. 

3. Clinical thermometer has a kink near the bulb while there is nokink in the laboratory thermometer. (Due to kink mercury does not fall down on its own in clinical thermometer.)

Correct Answer is: (b) 100 J

γ + 1 + 2/f = 1 + 2/6 = 4/3

ΔW/ΔQ = ΔQ - ΔU/ΔQ 

= 1 - n C_V ΔT/n C_p ΔT 

= 1 - 1/γ 

= 1 - 3/4 

= 1/4.

∴ ΔQ = 4ΔW = 100 J.

Correct Answer is: (d) 5/7

ΔQ = nC_p ΔT at constant pressure

ΔU = nC_V ΔT

Fraction = ΔU/ΔQ = C_V/C_p = 1/γ = 5/7 for diatomic gas.

1. higher temperature, lower temperature 

2. temperature 

3. kelvin 

4. expand, contract 

5. equilibrium

(a) The hotness of an object is determined by its temperature.
(b) Temperature of boiling water cannot be measured by a clinical thermometer.
(c) Temperature is measured in degree Celsius.
(d) No medium is required for transfer of heat by the process of radiation.
(e) A cold steel spoon is dipped in a cup of hot milk. It transfers heat to its other end by the process of conduction.
(f) Clothes of dark colours absorb heat better than clothes of light colours.

[✓] passed through 

Solids expand due to heat and come back to the original state if heat is removed.

1. If I heat a circular disk with a hole the diameter of the hole will increase. 

2. Because thermal expansion takes place when we heat the disk.

No. the temperature of the boiling water does not rise further after 100°C.

Approximate temperature of the tea when you drink 70°C.

Approximate temperature of cool lemon juice when you drink 20°C.

Common salt is added to ice in order to reduce the melting point so that ice will not melt soon.

Lower fixed point: On the Falirenheit scale is the mark at which pure ice melts. It is 32°F on Fahrenheit scale.

Upper fixed point: On the Fahrenheit scale is the mark at which water starts changing into steam at normal atmospheric pressure. It is 212°F.

(i) Ice point. Is the the mark on Celsius scale at which ice melts. Ice point on the Celsius scale is 0°C. 

(ii) Steam point. On the Celsius scale is the mark at which water changes into steam at normal atmospheric pressure. On Celsius scale it is 100°C.

(a) Heat is a form of energy. 

(b) Temperature determines the degree of hotness or coldness of a body. 

(c) On heating a body, its temperature rises. 

(d) We use a thermometer for measuring the temperature of a body. 

(e) The S.I. unit of temperature is kelvin. 

(f) In a thermometer, the commonly used liquid is mercury. 

(g) The temperature of a normal human body is 37 °C. 

(h) A person is said to have fever if his body temperature is more than 98.6 

(i) A hot metallic piece is placed in tap water contained in a bucket. Heat will flow from metallic piece to water. 

(j) The temperature of boiling water is 100°C.

(d) between 30°C and 50°C

1. In ice cubes, the force of attraction between the water molecules is more. So they are close together. 

2. When we heat them the force of attraction decreases and the ice cubes become water. 

3. when we heat the water, the force of attraction between the molecules decreases further. 

4. Hence they move away from one another and become vapor. 

5. Since water vapor escape to the surrounding,water level decreases. 

6. From this Activity we understand that heat energy causes change in the state of the substances.

A thermometer uses  

2. mercury 

4. A little space is left between two rails on a railway track

In places of hot climate it is advised that the outer walls of houses be painted white because white colour reflects most of the heat that falls on it or we can say it absorbs less amount of heat. Therefore, the temperature inside the house does not increase very much.

The air gets trapped between two layers of warm clothes. Air acts as insulator of heat. This layer prevents our body heat to escape in the surroundings. More layers of thin clothes will allow more air to get trapped and as a result we will not feel cold. So wearing more layers of clothing during winter keeps us warmer than wearing just one thick piece of clothing.

In places of hot climate, it is advised to paint the outer walls of houses as white because a light colour such as white reflects back most of the heat that falls on it. We can say that it absorbs less amount of heat and keeps the house cool.