nuclear physics Flashcards
Which of the following is the percentage of the original quantity of a radioactive material left after five half-lives approximately
3%
Fraction undecayed after 5 half-lives = (½)5 = 1/32
% = 1/32 × 100 = 3%
Principle of Hydrogen bomb in reactions.
Uncontrolled Fusion
The half-life of Uranium-238 is?
4.5 × 10 9 years
Half-life of U-238 is much higher than U-239. Half-life of U-239 is 23.5 minutes. That is why most of the naturally occurring uranium (99%) is U-238.
A source initially contains N0 nuclei of a radioactive nuclide. How many of these nuclei have decayed after a time interval of three half-lives?
7N0/8
One curie is approximately equal to the number of α-particles emitted from a radium of mass
1 gm
It was originally defined as ‘the quantity or mass of radium emanation in equilibrium with one gram of radium
Cobalt is absorbed in a whole body system by
the liver has natural ability to absorb cobalt
The necessary condition for nuclear fusion is
High temperature and high pressure
High temperature – The high temperature gives the hydrogen atoms enough energy to overcome the electrical repulsion between the protons.
High pressure – Pressure squeezes the hydrogen atoms together. They must be within 1 × 10-15 meters of each other to fuse.
if the half-life of an element is 10 second, the mean life will be:
14.4 sec
Tmean = 1.44T1/2
Half-life of radium-226 is:
1620 years
In Geiger counter:
The metal tube acts as the cathode and wire acts as the anode
Decay constant “λ” given by:
–(ΔN/N)/Δt
During fission process, the average number of neutrons emitted are:
2.5
Fission also results in the production of several neutrons, typically two or three. On the average, about 2.5 neutrons are released per unit and the energy of a neutron released per fission of a uranium atom are 2MeV.
Nuclear weak force is experienced during:
only beta decay
The most useful tracer is:
C – 14
The relation between the disintegration constant “λ” and the half-life T of a radioactive substance is:
λT = ln2
λT1/2 = ln2
λT1/2 = 0.693
T1/2 = 0.693/λ
Which of the following have no mass.
- A. Leptons
- B. Hydrons
- C. Bosons
- D. Meuons
Bosons are particles having no rest mass and no charge.
Radiation damage to living organism is primarily due to…
Ionization
Ionizing radiation is the most harmful because it can ionize molecules or break chemical bonds, which damages the molecule and causes malfunctions in cell processes.
According to Bohr model one of the following is a discrete quantity
angular momentum
nh/2π
Slope of the decayed atoms vs the time is a isothermal curve as shown below, the slope/ gradient of this slope represents
Activity = No/t = slope of graph
what is radius and energy directly proportional to?
Radius is directly proportional to square of number of orbit.
Energy is directly proportional to square of charge number.
how to calculate avg life time w t1/2
T1/2 / 0.693
avg lifetime is 1/decay constant
circulation of blood could be studied by radioactive isotope
Na - 24
the rate of decay of radiactive substance —— with time
decreases
what are isotones
diff elements having same neutron number, but diff nucleon number
