And his Atomic Theory
Niels Bohr was born on October 7, 1885 and he died on
November 18, 1962. He was born in Copenhagen, Denmark
and he died in the same area. His parents were Christian Bohr
and Ellen Adler, (Bohr). He had an older sister named Jenny,
who was born in 1883, and a younger brother named Harald who
was born in 1887. Harald and Niels were very close through out
his childhood and he was often heard saying that Harald was his
best friend all through his life.
Niels entered the Grammelholms school in October of 1891,
he attended this school for his complete secondary education.
He did fairly well in school but could never lay claim to a brilliant
mind, he usually came in forth or fifth in a class of twenty. In his
last two years in school Niels specialized in mathematics and
physics, he frightened his math teacher with his exceptional skills
and would work ahead in the physics textbook often pointing out
errors in the text. He was learned more about this subject than
he did from his teachers.
Bohr entered the University of Copenhagen in 1903. Physics
was his major and he had minors in mathematics and chemistry.
When he was in University he wouldn’t have been able to carry out
any experiments in physics because the University didn’t have a
laboratory, so he used his father’s physiology lab. And his first paper
describes some of the experiments he did in the lab, he dedicated this
paper to his brother, Harald. Due to this paper, Bohr, won the Gold
Medal for 1906 from the Royal Danish Academy of Sciences, this
was for his analysis of water jets being used to determine surface
tension. He got his masters degree from the University of
Copenhagen in 1909, and his doctorate in 1911for his thesis,
Studies on the electron theory of metals. This thesis was dedicated
to his father, who had died earlier in the year from a heart attack Bohr
was engaged to Margrethe Norlund, who, many say, placed a key role
in his successfulness, at the time of his father’s death.
In 1911 in the month of September Bohr went to England to study
with J J Thompson at Cambridge, he had hoped to spend a long
period of time with Thompson, but, unfortunately, they didn’t get
along. Lucky for him, he had met Rutherford earlier in that year and
went to study with him instead, this was right after Rutherford had
published his theory, which states that the bulk of the mass of an atom
can be found in the nucleus.
Bohr began developing his theory in June of 1912 He did his
fundamental work on the hydrogen atom eventually he even did some work
on some heavier atoms. Bohr returned to Copenhagen to continue
working on his theory which he completed to his satisfaction in and around
July of 1913. The University recommended his name for a chair in
theoretical physics, he expected his position to be confirmed within a year.
It wasn’t to be. He spent the next four years working with Rutherford and
his group yet again, he enjoyed his time with the group immensely,
participating in many break through activities.
His completed theory of the atom gave us the clue as to where, exactly,
electrons were found in an atom. He stated that electrons traveled on
fixed energy levels. Sort of like a ladder, these electrons could change
orbits but they would always be found in an orbit and there would always
be a certain number of electrons in the orbital.
Changing Energy Levels
The fact that there were certain orbits and energies in an atom was part of
Bohr’s theory. When these energies change levels there is a different color
given off.
Orbits were the key to Bohr’s theory
People a long time ago, believed that the northern lights were a sign from God.
Nobody would believe someone if he were to tell them that it could be explained
with science, and if it was a woman trying to tell them this they would often be
placed in an asylum or they would be placed in the care of one distant relative or
another. Now we know the truth they can be explained by science and Niels
Bohr is just the scientist to do it.
To answer this, we start with the sun whose energy production is far
from even and fluctuates on an 11 year cycle. Maximum production
occurs at the same time as high sunspot activity, processes on the sun's
surface throw particles far out in space. These particles are called the
solar wind and cause the northern lights.
The sun's surface temperature is approximately 6,000 0C, much cooler
than the interior which is several million degrees. In the sun's atmosphere
the temperature rises again to several million degrees. At such
temperatures, collisions between gas particles can be so violent that
atoms disintegrate into electrons and nuclei. What was once hydrogen
becomes a gas of free electrons and protons called plasma. This plasma
escapes from the sun's atmosphere through a hole in the sun's magnetic
field. As they escape, they are thrown out by the rotation of the sun in an
ever widening spiral - the so-called garden-hose effect. The name
originates from the pattern of water droplets formed if we swing a garden
hose around and around above out heads.
-Bohr
What causes the northern lights? Cont.
The garden hose effect.
The 11-year sunspot cycle
compared to northern lights activity.
Presentation done by
Becca Prescott,
Dane Huntley,
Maria Davis and
Samantha Stewert