21; nuclear physics Flashcards
If you swallowed an alpha-source and beta-source, which would be more dangerous to you?
alpha source because of its high ionizing power.
which element is used for the treatment of cancer in radiotherapy?
cobalt 60
gamma rays from cobalt 60 is used.
Define the term
‘‘critical mass’’
the minimum mass of uranium used to sustain the fission chain reaction is called critical mass.
what fraction of a radioactive sample decays after two half-lives have elapsed?
3/4 of radioactive sample decays after 2 half lives.
who suggested the existence of neutron and in which year?
Rutherford suggested the possibility of such particle and named it neutron in year 1920.
related to upper question.
who discovered neutron after 12 years in 1932 ?
James chadwick
define isotopes?
the atoms of an element having same number of proton but different number of neutrons.
which mehtod is used to separate isotopes?
it is not possible to separate them by chemical mehtod but separation can be done by physical methods such as mass-spectrography.
what is the principle of mass spectrograph?
it uses electric and magnetic field to sort out isotopes according to their masses.
what is binding energy?
the energy required to break the nucleus into its nucleons such as neutron and protons is called binding energy.
one amu is equal to?
1amu=931MeV
How would you define radioactivity?
Radioactivity is the act of emitting radiation spontaneously.
Radioactivity was firstly discovered by?
In 1896 by Henri Becquerel.
after him marie curie discovered two more elements.
half life of U-238 is?
4.5x10^9 years
what is the speed of alpha,beta nad gamma rays?
alpha=~10^7 m/s
beta=~1x10^8m/s
gamma=~3x10^8m/s
