## 2013-01-14

### Understanding Nuclear Energy : atomic mass unit and nuclear energy

Atomic mass unit (a.m.u)

The atomic mass unit (a.m.u) is used to measure the masses of atomic particles.

1 a.m.u is defined as (mass of carbon-12 atom / 12)

i.e. mass of carbon-12 atom divided by 12.

It is known that the mass of one carbon-12 atom is 1.99 X 10^ - 26 kg.

Therefore,

1 a.m.u = (1.99 X 10^ - 26 kg / 12)

= 1.66 X 10 ^ - 27 kg

The value is very close to the mass of one proton or neutron.

The atomic mass unit (a.m.u) is often used in nuclear physics as it is easier unit to represent masses of minute particles.

Nuclear Energy

In a radioactive disintegration, a process where one element changes into another is called transmutation.

The mass of daughter particles and other particles produced is less than that of the different particle. This difference in mas is called mass defect or mass loss.

Mass defect = mass of parent particle - Total mass of daughter particles and other particles produced.

The mass loss is converted into energy.

According to Einstein's principle of Mass-Energy Conservation, the change of energy is linked to the change of mass by the equation;

E = mc^2

m = mass change, kg
c = speed of light, ms-1
E = energy changed, J