Temperature

Question 1

state the law of conservation of energy

Answer 1

energy is never created or destroyed, only transferred from one form to another

Question 2

define thermal energy

Answer 2

Thermal energy is the energy transferred from a region of higher temperature to a region of lower temperature

Question 3

what does temp tell us

Answer 3

direction of energy flow when 2 regions are in contact- hotter to cooler

Question 4

define thermal equilibrium

Answer 4

When two substances in physical contact with each other no longer exchange any heat energy and both reach an equal temperature

Question 5

what is A thermometer

Answer 5

A thermometer is any device that is used to measure temperature

Question 6

what property does a liquid in glass thermometer depend on

Answer 6

density of liquid. it expands with temp increase and moves along capillary tube

Question 7

what property does a gas thermometer depend on

Answer 7

Volume of gas at constant pressure. As the temperature of the gas increases, its volume increases and vice versa (how quick volume increases with temp)

Question 8

what property does a thermistor based thermometer depend on

Answer 8

resistance.
it decreases with temp increase. changes rapidly over narrow range of temps.
Non linear so curve so must be calibrated

Question 9

what is a thermocouple

Answer 9

an electrical device used as the sensor of a thermometer
It consists of two wires of different metals attached to each other, producing a junction on one end. The opposite ends are connected to a voltmeter. When this junction is heated, an e.m.f. is produced between the two wires which is measured on the voltmeter. The greater the difference in temperature between the wires, the greater the e.m.f

Question 10

thermocouple graph

Answer 10

non linear so needs calibration

Question 11

purpose of the Kelvin/thermodynamic scale

Answer 11

overcome issue with sclaes of temp
said to be an absolute scale that is not defined in terms of a property of any particular substance
This is because thermodynamic temperaturesdo not dependon the property of any particular substance

Question 12

define absolute zero on the kelvin scale

Answer 12

The lowest temperature possible. Equal to 0 K or -273.15 °C

Question 13

define absolute zero in kinetic terms

Answer 13

The temperature at which the atoms and molecules in all substances have zero kinetic and potential energy (so internal energy is also zero)

so impossible to remove energy from sth at 0K

Question 14

relationship between C and K temp

Answer 14

A change in a temperature of 1 K is equal to a change in temperature of 1oC

Question 15

how to go from K to C

Answer 15

-273.15

Question 16

technical word for thermistors and thermocouples

Answer 16

temp sensors

Question 17

advantages of thermistor

Answer 17

It is veryrobustie. strong and doesn’t easily break

Highly sensitiveover a narrow range of temperatures

Question 18

disadvantages of thermistor

Answer 18

Only anarrow rangeof temperatures can be read

Difficult to get accurate readings

Non-linear readings

Question 19

advantages of thermocouple

Answer 19

It isrobust
Can detect awide rangeoftemperatures (Veryaccuratereadings)
Low thermal capacity, therefore, quicker acting
Small so can measure at any point
Long conducting wires allow the operator to be at a distance from the thermocouple

Question 20

disadvantages of thermocouple

Answer 20

variation means calibration is required

Question 21

give 2 observations which woud support the idea that temperature doesnt measure amount of thermal energy/heat in a body

Answer 21

• when heat is added to melt/boil temp doesnt change
• 2 objects of diff mass and same material would need diff amounts of heat to reacht at temp (iebig tub a lot energy but small temp and vice versa)

Question 22

when temp is not changing its either cos of change in state or …

Answer 22

rate heat lost= heat input

Question 23

whats sensitivity

Answer 23

large change in a property for small change