Transfer of thermal energy and its effects

Question 1

What is used to measure temperature?

Answer 1

Thermometer

Question 2

What is the SI unit of temperature?

Answer 2

Kelvin (K)

Question 3

Is there a temperature below zero K? What is this called?

Answer 3

0 K is the lowest possible temperature anywhere and is hence called the ABSOLUTE ZERO

Question 4

What is special about heat?

Answer 4

It is not a physical entity and cannot be contained in a body

Question 5

What is heat?

Answer 5

It is the transfer of thermal energy from a region of high temperature to a region of Low temperature. The transfer will stop when both regions have reached the same temperature, also known as thermal equilibrium.

Question 6

What is temperature?

Answer 6

It is the measurement of the average kinetic energy of molecules in a body

Question 7

What is thermal energy and its SI unit?

Answer 7

It is the energy in a body due to its temperature and is measured in Joules (J)

Question 8

Thermal energy flows from a region of higher temperature to a region of lower temperature until both regions have reached the same temperature. What is this state called?

Answer 8

Thermal equilibrium

Question 9

What happens when object are heated? (Macroscopic view, give general terms)

Answer 9

They gain thermal energy and expand

Question 10

What happens when object are cooled? (Macroscopic view, give general terms)

Answer 10

They lose thermal energy and contract.

Question 11

Rank the three states of matter from the most expandable to the least

Answer 11

Gases, liquids, solids

Question 12

What increases as a substance expands

Answer 12

It’s volume

Question 13

State the formula for density

Answer 13

Mass / volume

Question 14

State the formula for mass

Answer 14

Volume x density

Question 15

State the formula for volume

Answer 15

Mass / density

Question 16

What happens to water when it is cooled below 4 degrees celcius?

Answer 16

It expands and changes state to form ice slowly as it hits zero degrees

Question 17

What does a thermostat contain and what is its function?

Answer 17

It contains a bimetallic strip and its function is to keep the temperature in appliances constant.

Question 18

What is 0 K in degrees celcius?

Answer 18

-273 degrees celcius

Question 19

What is ice point? Assigned value?

Answer 19

It is the temperature of pure melting ice at a standard atmospheric pressure. It is assigned the value of zero degrees celcius.

Question 20

What is steam point? Assigned value?

Answer 20

It is the temperature at which pure boiling water changes into steam at a standard atmospheric pressure. It is assigned the value of 100 degrees celcius.

Question 21

Formula for finding unknown temperature?

Answer 21

(Length at unknown
degrees celcius- length at lowest temp)/ length at highest temp- length at lowest temp ) x difference between highest and lowest temps

Question 22

What is the lowest temperature in degrees celcius?

Answer 22

-273 degrees celcius

Question 23

What is the absolute zero?

Answer 23

It is the lowest possible temperature where all particles stop moving

Question 24

How to find kelvin from celcius and vice versa?

Answer 24

(To find Kelvin)— Kelvin is kind so we add 273 to it
(To find Celcius) — celcius is cruel, so we minus 273 from it)

Question 25

Physical property used in electro couple

Answer 25

Voltage

Question 26

Physical property used in electric resistor

Answer 26

Resistance

Question 27

Physical property used in constant volume gas

Answer 27

Pressure

Question 28

Physical property used in liquid in glass

Answer 28

Volume

Question 29

What is conduction?

Answer 29

Conduction is the transfer of thermal energy through a material without obvious movement of the medium itself

Question 30

How does conduction work?

Answer 30

When one end of a rod is heated, the atoms there gain energy and start to vibrate. They collide with the less energetic neighbouring atoms. Upon collision, some of the energy is transferred to these neighbouring atoms causing them to gain kinetic energy and vibrate faster. In this way, thermal energy is conducted throughout the rod.

Question 31

Why are metals better conductors of thermal energy than non-metals?

Answer 31

Along with the transfer of thermal energy through particles, thermal energy is also transferred through free electrons in metals. Upon heating, free electrons gain energy and begin to vibrate faster. They are free to travel between the spaces of vibrating particles and colliding with other free electrons and particles, transferring some of its energy to them, causing them to vibrate faster. Since both the process of transfer via free electrons and particles are taking place in metals, the process of the transfer of thermal energy in metals is much faster than that in non-metals. Hence, metals are better conductors of thermal energy than non-metals.

Question 32

Why are solids better conductors of thermal energy than liquids and gases?

Answer 32

The particles in solids are packed closer together than in liquids or gases, and hence the transfer of thermal energy through the particles is able to take place faster.

Question 33

Even though styrofoam and wood are solids, why are they poorer conductors of thermal energy than liquids?

Answer 33

They contain air pockets and since air is a poorer conductors of thermal energy than liquid, solids such as styrofoam and wood are poorer conductors of thermal energy than liquids

Question 34

Why is a vacuum a good insulator?

Answer 34

For conduction to take place, matter should exist for thermal energy to be transferred. Since a vacuum does not contain any matter, it is a perfect insulator since conduction cannot take place.

Question 35

What is radiation?

Answer 35

Radiation is the process by which thermal energy is transferred by electromagnetic waves

Question 36

What is special about radiation that does not apply to conduction and convection?

Answer 36

It can take place in a vacuum, it does not require a medium

Question 37

What happens when radiation is absorbed?

Answer 37

When absorbed, the energy of infrared radiation is transformed into thermal energy of the receiving body

Question 37

What happens when radiation is absorbed?

Answer 37

When absorbed, the energy of infrared radiation is transformed into thermal energy of the receiving body

Question 38

What do all objects have in common in terms of radiation?

Answer 38

All objects emit and absorb infrared radiation

Question 39

What is the rate of energy transfer via radiation affected by?

Answer 39

It is affected by ACTT— surface area, surface colour and texture, and surface temperature

Question 40

If you are a poor absorber/ radiator, you are a good

Answer 40

Reflector

Question 41

If you are a good absorber/ radiator, you are a poor

Answer 41

Reflector

Question 42

What is the use of insulators?

Answer 42

They reduce the transfer of thermal energy in a house

Question 43

What are double glazed windows?

Answer 43

They are 2 sheets of glass and they are filled with air/noble gas