Unit 6

Question 1

Heat transfer

Answer 1

The movement of thermal energy from one place to another. When objects are at the same temperature, they are in thermal equilibrium and there is no heat transfer between them

Question 2

Specific heat capacity

Answer 2

The heat capacity per unit mass of a given substance. The amount of energy required to heat 1kg of mass of a substance 1 K

Question 3

Contact thermometry

Answer 3

Contact thermometry involves placing a temperature sensor in close proximity to the object being measured (such as touching or immersing). Heat flows to or from the sensor until the sensor and object reach thermal equilibrium

Question 4

Examples of contact thermometry

Answer 4

• liquid in glass thermometer
  -bimetallic temperature sensor
  -Resistance Temperature Detector
  -thermistors
  -thermocouples

Question 5

Non contact thermometry

Answer 5

Fill in

Question 6

Pros and cons of Resistance Temperature Detectors

Answer 6

Pros:
-linear
-accurate
-repeatability
-good sensitivity

Cons:
-relatively expensive
-self heating errors

Question 7

Pros and cons of thermistors

Answer 7

Pros:
-small size
-inexpensive
-suited for remote sensing

Cons:
-highly non-linear
-narrow temp range
-fragile

Question 8

Peltier effect

Answer 8

A current passed between the junctions of two dissimilar metals will cause one of the junctions temperatures to increase and the other to decrease. Therefore, a temperature differential will exist between the two junctions

Question 9

Thomson effect

Answer 9

Positive: if a conductor has a temperature gradient along its length and current flow is in the same direction as heat flow, then the temperature will increase

Negative: if the current flow is in the opposite direction to the heat flow, then the temperature will decrease