What are these objects?
Order them from coldest to hottest
What are these objects?
Order them from coldest to hottest
kT is about how much energy
particles have at temperature T in
kelvin
Worked example
• On a nice summer’s day (27 oC) how much energy would the particles have?
Worked answer
JkT
KJKkTQ
JKk
KCT o
21
123
123
101.4
3001038.1
1038.1
30027
Example questions
• Determine the amount of energy a particle would have if it were:
– In the centre of the Sun– In the centre of a supernova– In Mars’ northern polar cap– In interstellar space
Location k / JK-1 T / K kT / J
Centre of the Sun 1.38 x 10-23
Centre of a supernova 1.38 x 10-23
Within magma 1.38 x 10-23
Within Mars' northern polar cap
1.38 x 10-23
In interstellar space 1.38 x 10-23
Location k / JK-1 T / K kT / J
Centre of the Sun 1.38E-23 1.50E+07 2.07E-16
Centre of a supernova 1.38E-23 1.00E+11 1.38E-12
Within magma 1.38E-23 1.00E+03 1.38E-20
Within Mars' northern polar cap
1.38E-23 2.30E+02 3.17E-21
In interstellar space 1.38E-23 3.00E+00 4.14E-23
If T = 10 000 K
eVkT 1
The eV
• The energy gained by an electron as it moves through a potential difference of 1 V
JW
VCW
QVW
Q
WV
19
19
106.1
1106.1
Show kT = 1eV (T = 10000K)
eVkT
JeV
JkT
KkT
KT
1
106.11
1038.1
100001038.1
10000
19
19
24
Ideal gaskT
2
1
kT2
1
kT2
3 kT2
1
kT2
1
kT2
1
kT2
1
kT3
Hotter and hotter
Life at T = 300 K
Fires and kilns, T = 1500 K
White hot at the Sun’s surface, T = 6000 K
Hotter still: inside the Sun, T = 6000000 K