I'm not sure what level of answer you are looking for - the one above is fine, but here's a less sophisticated one.
Consider a dipole made up of a positive and negative charge separated by a small distance. If you make these charges swap positions, backward and forwards then you have an oscillating electric dipole that will generate electromagnetic waves.
Now consider a small conducting loop and pass a current through the loop that goes one way around and then the other. This is called an oscillating magnetic dipole and also produces electromagnetic waves.
In certain circumstances, an atom (or molecule or nucleus) can behave like an oscillating electric dipole or an oscillating magnetic dipole (or even electric/magnetic quadrupoles, octopoles etc.). Some reasonably sophisticated quantum mechanics tells us which of these possibilities is "allowed" or "forbidden" when an atom switches from one quantum state to another.
If during the switch the atom can behave like an oscillating electric dipole, then this is usually (for visible/IR/radio radiation at least) more efficient than the oscillating magnetic dipole or electric quadrupole etc. This would be termed an electric dipole transition. However, for certain changes of quantum state, the atom cannot behave like an oscillating electric dipole and the transition can only proceed (less efficiently - often called a "forbidden transition" in astrophysics) by the atom behaving like an oscillating magnetic dipole - i.e. a magnetic dipole transition.
Selvalakshmi,
At the risk of parrotting texts on particle physics, the electric dipole transition represents a coupling between a charged particle and the electric component of an electromagnetic field.
The magnetic dipole transition (I bet you can see what's coming next...) etc.etc.
By convention the hamiltonian of the interaction between a charged particle and an electromagnetic field is broken down into two parts - that resulting from the B field, and that from the E field: the magnetic and electric components respectively. Either transition may be permitted or disallowed depending on selection rules.
Needless to say, there are excellent wikipedia pages on both matters.
I'm not sure what level of answer you are looking for - the one above is fine, but here's a less sophisticated one.
Consider a dipole made up of a positive and negative charge separated by a small distance. If you make these charges swap positions, backward and forwards then you have an oscillating electric dipole that will generate electromagnetic waves.
Now consider a small conducting loop and pass a current through the loop that goes one way around and then the other. This is called an oscillating magnetic dipole and also produces electromagnetic waves.
In certain circumstances, an atom (or molecule or nucleus) can behave like an oscillating electric dipole or an oscillating magnetic dipole (or even electric/magnetic quadrupoles, octopoles etc.). Some reasonably sophisticated quantum mechanics tells us which of these possibilities is "allowed" or "forbidden" when an atom switches from one quantum state to another.
If during the switch the atom can behave like an oscillating electric dipole, then this is usually (for visible/IR/radio radiation at least) more efficient than the oscillating magnetic dipole or electric quadrupole etc. This would be termed an electric dipole transition. However, for certain changes of quantum state, the atom cannot behave like an oscillating electric dipole and the transition can only proceed (less efficiently - often called a "forbidden transition" in astrophysics) by the atom behaving like an oscillating magnetic dipole - i.e. a magnetic dipole transition.
Dimitrov and Jeffries are well explained everything. But it was asked a simple question: What is the difference between them?
So, the simple answer.
Electric dipole is two electric charges.
The magnetic dipole is not exists.
However, the field of currents, which are located in a limited area of space in the far distance from this area with a good degree of accuracy is described by the same formula. In this formula, the electric charges are replaced by virtual magnetic charges.
Electric and magnetic dipole transition rates are first perturbation approximations. Perhaps this name is not very good because it can be confused with the idea of classical electric and magnetic dipoles. What is important to remark is that the electromagnetic radiation emitted or absorbed by an atom have transitions forbidden between certain atomic states which basically are obtained using Clebsch-Gordan coefficients in this first approach of the electromagnetic field. Let me to put the fundamental:
1. The transition rates are zero unless the difference between m initial and the m final is -1,0,+1.
2. In the same form the orbital momenta have to lf-li=-1,0,+1.
3. Finally, lf-li= odd integer
This means that , in the case of electric dipole transitions, the final and initial states must have different parities. For instance transitions like
1s to 2s
2p to 3p etc
are forbidden, while transitions
1s to 2p
2p to 3s etc
are allowed.
In contrast magnetic dipole transitions and quadrupole couple states with the same parity. A good book for seeing this topic is :
D.Griffiths, Introduction to Quantum Mechanics, Prentice-Hall,1995.
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