Q: In which of the following process convection does not take place primarily?

\$\textbf{Explanation:}\$\$\bullet\$In convection, transfer of heat took place by movement of gaseous and liquid molecules.\$\bullet\$It generally happens in liquid and gas only where bulk portion is fluid. Sea and land breeze, trade wind and boiling water are example of such fluids. So, in those heat transfer is because of convection. But in bulb filament, resistance is responsible for transferring the heat which is example of conduction. So, in warming of glass bulb due to filament convection doesn’t take place. Hence, option D is the correct answer.

Question 1

Why do we wear cotton clothes in Summer ?

Accepted Answer

We wear cotton clothes during summer as cotton absorbs sweat from the body, exposing to the atmosphere for easy evaporation. As we tend to sweat more during summer and cotton fabric absorbs sweat and help body to cool down. Cotton allows better air circulation which helps to absorb and removing body moisture caused by sweat via evaporation.

Question 2

State similarities and differences between the laboratory thermometer and the clinical thermometer.

Accepted Answer

Similarities:Bulbs contain mercury.Glass tubes are long, narrow and uniform.Differences:The clinical thermometer is used to measure body temperature, however, laboratory thermometer is not used for the purpose of measuring body temperature.The temperature range of clinical thermometers is 35&#176;C to 42&#176;C and that of laboratory thermometers is -10&#176;C to 110&#176;C.The least count of both the thermometers is different.The clinical thermometer is can be tilted while reading the temperature values whereas laboratory thermometer need to be kept upright.

Question 3

Draw a neat labelled diagram of a laboratory thermometer.

Accepted Answer

Labeled diagram of of a laboratory thermometer is shown in the figure below:

Question 4

In which of the following process convection does not take place primarily?

Accepted Answer

$\textbf{Explanation:}$$\bullet$In convection, transfer&#10;of heat took place by movement of gaseous and liquid molecules.$\bullet$It generally&#10;happens in liquid and gas only where bulk portion is fluid. Sea and land&#10;breeze, trade wind and boiling water are example of such fluids. So, in those&#10;heat transfer is because of convection. But in bulb filament, resistance is&#10;responsible for transferring the heat which is example of conduction. So, in&#10;warming of glass bulb due to filament convection doesn&#8217;t take place.&#10;&#10;Hence, option D is&#10;the correct answer.

Question 5

A) Heat transfer by conduction and convection require a material medium.B) Heat transfer by radiation doesn't require a material medium.

Accepted Answer

Conduction and convection are processes where heat is transferred by the collision of molecules. Hence, for these processes to take place, we need a material medium.In radiation, heat travels as electromagnetic waves which do not require a medium to travel. Its transfer mechanism is completely independent of the medium.

Question 6

When two bodies at different temperatures are placed in thermal contact with each other, heat flows from the body at a higher temperature until they both acquire the same temperature. Assuming that there is no loss of heat to the surroundings, then:

Accepted Answer

Heat is a form of energy that gets transferred from one medium or object to another medium/object. Suppose if we a colder body and a hotter body and if it brought in contact, the heat gets transferred from the hotter body to colder body until the system of hotter & colder attains equilibrium.When two bodies at different temperatures are placed in thermal contact with each other, heat flows from the body at a higher temperature until they both acquire the same temperature. Assuming that there is no loss of heat to the surroundings, then The heat lost by the hotter body will be equal to the heat gained by the colder body.option D is correct

Question 7

A beggar wrapped himself with a few layers of newspaper on a cold winter night. This helped him to keep himself warm because

Accepted Answer

The correct answer is option (b) Air trapped among the layers of newspaper is a poor conductor of heat. So. this helps him to keep himself warm.

Question 8

The process of transfer of heat by the movement of particles of medium from one place to another is called

Accepted Answer

Process of heat transfer through movement of particles of medium from one place to another is convection.

Question 9

Which of the following is an example of convection?

Accepted Answer

Convection is a form of heat transfer where a large number of molecules move from one place to another. An overhead fan works precisely by this method: it sends cooler air molecules down into a hot room, cooling the temperature of the room. The heat of the sun and the cooking action of a microwave are both forms of radiation, while the heat on a frying pan and the cooling action of ice cubes are both forms of conduction.

Question 10

The best conductor of heat is

Accepted Answer

Silver is the best conductor of heat among the given options.