Current Affairs JEE Main & Advanced

Category : JEE Main & Advanced

(1) In nuclear physics, a convenient unit of mass is the unified atomic mass unit abbreviated u.

(2) The amu is defined as \[\frac{1}{12}th\] mass of a \[_{B}{{C}^{12}}\] at on.

(3) 1 amu (or 1 u) =\[1.6605402\times {{10}^{27}}kg\].

(4) Masses of electron, proton and neutrons :

Mass of electron\[\text{(}{{m}_{e}})\text{ }=\text{ }9.1\times {{10}^{31}}kg=\text{ }0.0005486\,\,amu\],

Mass of proton \[\text{(}{{m}_{p}})=1.6726\times {{10}^{27}}kg=\text{ }1.007276\,\,amu\]

Mass of neutron \[\text{(}{{m}_{n}})=1.6750\times {{10}^{27}}kg=1.00865\,\,amu\],

Mass of hydrogen atom \[\text{(}{{m}_{e}}+{{m}_{p}}\text{)}=1.6729\times {{10}^{27}}kg=\text{ }1.0078\,\,amu\]

(5) The energy associated with a nuclear process is usually large, of the order of MeV.

(6) According to Einstein, mass and energy are inter convertible. The Einstein's mass energy relationship is given by \[E=m{{c}^{2}}\]

If \[m=1\,\,amu,\,\,c=3\times {{10}^{8}}m/sec\] then \[E=931\,MeV\] i.e. 1 amu is equivalent to 931 MeV or \[1\,\,amu\,\,(or\text{ }1u)=931MeV\]

\[(1\,u){{c}^{2}}=931MeV\]\[\Rightarrow \] \[1u=931\frac{MeV}{{{c}^{2}}}\] or \[{{c}^{2}}=931\frac{MeV}{u}\]

Neutral atomic masses for some light nuclides