Heat Test

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Heat Test - 15

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Weekly Quiz Competition

Question 1
1 / -0

Warmer air is:

A
Lighter than cold air

B
Heavier than cold air

C
Both have equal weights

D
We cannot say

Solution

In warm air the molecules are farther away from each other because of more energy, hecne density is less , that is , less molecules per unit volume ,hence it is lighter. While in cold air molecules are closer (density is more ) hence it is heavier.
Question 2
1 / -0

The phenomenon involved in sea breeze and land breeze is

A
Convection

B
Conduction

C
Radiation

D
None

Solution

$$Sea \ breeze:$$ They are formed during the day time when land and sea both are heated equally by the sun, but land is heated up more quickly, thus air above land due to heat becomes lighter and rises up due to $$convection.$$ Thus pressure decreases and cold and humid air above the sea blowing towards land.
$$Land \ breeze:$$ They are formed during the night when sea water and land both lose heat. Land loses heat energy fast and cools more rapidly as compared to the sea. Sea water being at higher temperature, the air becomes lighter and rises up due to $$convection$$. So air from land starts blowing towards the sea and gives rise to a land breeze.
In both the processes, the transfer of heat takes place by actual movement of the particles of the medium.
Question 3
1 / -0

Conduction cannot take place in:

A
Copper

B
Iron

C
Aluminium

D
Vacuum

Solution

A medium is required for conduction to take place. Since vacuum does not have a medium, conduction does not take place.
Question 4
1 / -0

In convection currents, heat is transferred upwards

A
horizontally

B
diagonally

C
vertically

D
none of these

Solution

Convection is mode of heat transfer in which medium particles moves while transferring the heat. ex- Process of Heating of water; water molecules near the bottom areas of container takes heat and rise the top at the same time another water molecules come down. this goes continuously and water get warm. this phenomena of heat transfer is called convection heat transfer. and heat current flow from bottom to top ie vertically upward.
Question 5
1 / -0

The freezer in a refrigerator is fitted near the top :

A
to keep it away from the hot compressor which is near the bottom.

B
because of convenience.

C
so that it can cool the whole interior by setting up convection currents.

D
without any specific purpose.

Solution

Answer is C.

In a refrigerator, the freezer at the top of the unit contains the evaporator, which cools the air. Cold air is more dense than warmer air, so it sinks to the bottom of the freezer. There the cold air flows through vents (usually inside the meat keeper) into the refrigerator cabinet where it sinks to the bottom of the fridge (the crisper). Air warmed by the contents of the fridge rises as the cold air displaces it, and the 'warm' (only a few degrees difference) air enters into the freezer compartment where the cycle begins again.
Hence, the freezer in a refrigerator is fitted near the top so that it can cool the whole interior by setting up convection currents.
Question 6
1 / -0

A thermometer is used to measure

A
Heat

B
Thermal capacity

C
Water equivalent

D
Temperature

Solution

A thermometer is an instrument that measures temperature. It can measure the temperature of a solid such as food, a liquid such as water, or a gas such as air. The three most common units of measurement for temperature are Celsius, Fahrenheit, and kelvin. The Celsius scale is part of the metric system.
Question 7
1 / -0

Iron glows in red colour when it is heated to very high temperature. The reason for this is :

A
Heat we supply consumes red colour at high temperature

B
Mechanical energy is being converted into heat energy

C
All metals glow in red colour when heated

D
Heat energy is being converted into light energy

Solution

Iron glows in red colour when it is heated to very high temperature cause heat energy is being converted into light energy.
Question 8
1 / -0

Which of the following is a good conductor of heat?

A
Plastic

B
Mercury

C
Water

D
Alcohol

Solution

Mercury is categorized under metasl and we know that metals conduct heat better than non-metals.
So mercury is the answer.
Question 9
1 / -0

The air becomes heated by

A
Conduction

B
Convection

C
Radiation

D
Expansion

E
Diffusion

Solution

Convection is a mode of heat transfer where the molecules near the heat source get heated up. They absorb energy, expand, become less dense, and rise upwards.

On the other hand, the relatively colder molecules sink to the bottom and eventually get heated up again. Thus air gets heated by convection.
Question 10
1 / -0

Essential requirement to propagation Heat energy:

A
no medium

B
gaseous medium

C
solid medium

D
liquid medium

Solution

Heat energy can propagate by radiation, which is a mode of propagation of heat energy. Radiation doesn't require any medium hence heat energy essentially requires no medium for propagation .

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Re-Attempt Weekly Quiz Competition

Heat Test - 15

Result

Heat Test - 15

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SHARING IS CARING

Question 1

Lighter than cold air

Heavier than cold air

Both have equal weights

We cannot say

Solution

Question 2

Convection

Conduction

Radiation

None

Solution

Question 3

Copper

Iron

Aluminium

Vacuum

Solution

Question 4

horizontally

diagonally

vertically

none of these

Solution

Question 5

to keep it away from the hot compressor which is near the bottom.

because of convenience.

so that it can cool the whole interior by setting up convection currents.

without any specific purpose.

Solution

Question 6

Heat

Thermal capacity

Water equivalent

Temperature

Solution

Question 7

Heat we supply consumes red colour at high temperature

Mechanical energy is being converted into heat energy

All metals glow in red colour when heated

Heat energy is being converted into light energy

Solution

Question 8

Plastic

Mercury

Water

Alcohol

Solution

Question 9

Conduction

Convection

Radiation

Expansion

Diffusion

Solution

Question 10

no medium

gaseous medium

solid medium

liquid medium

Solution

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