7 Circular Current Loop as a Magnetic Dipole
Circular Current Loop as a Magnetic Dipole
- A current carrying wire can be considered as a magnetic dipole.
- Its upper face has current flowing in anti-clockwise direction.
∴ It has North polarity.
- Its lower face has current flowing in clockwise direction.
∴ It has South polarity.
- Magnetic dipole moment of current loop (M) is
- directly proportional to strength of current (I)
∴ M ∝ I
- directly proportional to the area of enclosed loop (A)
∴ M ∝ A
M = kIA
Where, k is constant of proportionality
For k = 1,
M = AI
- For N such turns,
Magnetic dipole moment of a revolving electron
- An electron of charge e revolves in a path of radius r having a uniform angular velocity ω.
- Current,
Where, t is period of revolution of electron
- Let r be the radius of the orbit.
∴ Area of the orbit, A = πr2
- Magnetic moment of the atom, M = iA
- According to Bohr’s theory, an electron in an atom can revolve only in a certain stationary orbit.
- Therefore, the angular momentum of electron (mvr) is an integral multiple of
.
From equation (1),
Where, μB is the least value of atomic dipole moment known as Bohr’s magneton.