Temperature

Question 1

S.I. unit for temperature

Answer 1

K (Kelvin)

Question 2

Relationship between ºC and K

Answer 2

__ K = __ ºC + 273

Question 3

What is the difference between heat energy and temperature?

Answer 3

Temperature indicates the heat energy level of a body whereas heat energy refers to the internal energy of a body

Question 4

What instruments are used to measure temperature? (3)

Answer 4

Liquid in glass thermometers
Digital thermometers
Laboratory thermometers

Question 5

Examples of liquid in glass thermometers (4)

Answer 5

Clinical thermometer
Laboratory thermometer
Mercury in glass thermometer
Alcohol in glass thermometer

Question 6

What are the liquids mercury and alcohol called?

Answer 6

Thermometric liquids

Question 7

2 properties used for measurement of temperature

Answer 7

Volume and Voltage

Question 8

Which thermometer uses voltage to measure temperature?

Answer 8

Thermocouple thermometer

Question 9

What makes a physical property suitable for measurement of temperature?

Answer 9

The change in the physical property must be proportional to changes in temperature so that the scale is linear

Question 10

Define ice point

Answer 10

The temperature of pure melting ice at standard atmospheric pressure. 0ºC

Question 11

Define steam point

Answer 11

The temperature of pure boiling water at standard atmospheric pressure. 100ºC

Question 12

How are fixed points used when calibrating a thermometer?

Answer 12

1) Place the thermometer in ice and mark its level (0ºC)
2) Place the thermometer in boiling water and mark its level (100ºC)
3) The distance between the two marks is divided into 100 equal sections

Question 13

What is the temperature of a healthy human?

Answer 13

37.5ºC

Question 14

3 differences between laboratory and clinical thermometer?

Answer 14

Clinical thermometer:

1) Short range (35ºC - 42ºC)
2) Presence of constriction
3) Used to measure temperatures of patients

Laboratory thermometer:

1) Long range ( -10ºC - 110ºC)
2) No constriction
3) Used to measure temperature of air and solutions

Question 15

What is the purpose of the constriction in a clinical thermometer?

Answer 15

It prevents back flow of mercury/alcohol when it is removed from the patients mouth

Question 16

5 differences between mercury and alcohol thermometer

Answer 16

Mercury:

1) Costly
2) Poisonous
3) Less visible
4) Does not stick to glass
5) Accurate

Alcohol:

1) Cheap
2) Not poisonous
3) More visible
4) Sticks to glass
5) Not as accurate

Question 17

What does the sensitivity of a thermometer refer to?

Answer 17

The change in volume or height of the thermometric liquid for each degree change in temperature

Question 18

When is a thermometer sensitive?

Answer 18

When the height of the thermometric liquid thread changes by a larger amount per degree change in temperature

Question 19

Factors affecting the sensitivity of a thermometer (3)

Answer 19

1) The expansion/contraction of the thermometric liquid when there is a change of temperature
2) The diameter of the capillary tube
3) The volume of the thermometric liquid in the bulb of the thermometer

Question 20

Does alcohol or mercury expand more? By how much?

Answer 20

Alcohol expands four times more than mercury for the same rise in temperature

Question 21

What will a smaller diameter of the capillary tube do to the sensitivity of a thermometer?

Answer 21

The thermometer will be more sensitive as it allows the thermometric liquid to move a longer way through the capillary tube for a small change in temperature

Question 22

What will a greater volume of the thermometric liquid do to the sensitivity of the thermometer?

Answer 22

The thermometer will be more sensitive

Question 23

What does the range of a thermometer indicate?

Answer 23

It gives an indication of the minimum and maximum temperature it can measure

Question 24

What is the linearity of a thermometer?

Answer 24

It is the volume of or height of the thermometric liquid in the capillary tube varies uniformly with temperature

Question 25

When does a thermometer have a linear scale?

Answer 25

If the height of the alcohol thread in the capillary tube changes by equal number of divisions with equal change in temperature

Question 26

How does a thermocouple thermometer work?

Answer 26

It measures temperature through the potential difference between bodies having a difference in their temperature

Question 27

Advantages of using a thermocouple thermometer (3)

Answer 27

1) It can measure rapid varying temperature
2) It has a large temperature range
3) It can measure temperature at a point