metastable state in laser.
In order to achieve population inversion, we must have an energy state which has a long lifetime i.e electron can stay there for sufficiently long time such an energy state is called as metastable state.
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Modified ampere's circuital law.
It states that the line integral of the magnetic field induction B around any closed path or circuit is equal to the ‘μo’times sum of conduction current & displacement current. I.e ∮B • dl = μo (Ic+Id) Where, Ic=conduction current Id=displacement current Value of displacement current ‘Id’ is Id = ε d∅/dt Where, ∅ = electric flux It is also known as Ampere Maxwell's circuital law.
larmors precession.
An electron moving around a nucleus of an atom is equivalent to magnetic dipole. When the atom is kept in an external magnetic field then electron orbit preceses about the external magnetic field direction. This precession is called larmors precession. I.e electronic orbit or angular momentum(L) of electron preceses about the external magnetic field. Larmors frequency, f =eB/4πm I.e larmors frequency is independent of angle between L and B. Where , B= external magnetic field e= charge of electron m= mass of electron
Electric quadrupole moment.
The deviation from the spherical symmetry is expressed in terms of a quantity known as electric quadrupole moment(Q). Q = (2/5) ze(b²-a²) For spherical symmetry Q = 0 For horizontal elliptical symmetry Q= -ve For vertical elliptical symmetry Q= +ve
Baryon number.
According to conservation of baryon number net baryon number remains conserved during every reaction of elementary particles. Baryon number (B)= +1 for all nucleons and hyperons. Baryon number (B)=-1 for antiparticles in the family of nucleons and hyperons. Baryon number (B)= 0 (other than baryons)
concept of quarks.
A quark has no internal structure but it is supposed to be fundamental constituent of matter.Quarks have fractional charge(i.e Q≠ne).Their are 6 flavours of quarks 1. Up quark(u) 2. Down quark(d) 3. Strange quark(S) 4. Charm quark(C) 5. Bottom quark(b) 5. Top quark(t) ★The number of quarks is always conserved in all interactions. Quarks are unstable & therefore, they have been ever observed as free particles.They are always found confined in baryons & mesons.