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, μ_B is the least value of atomic dipole moment known as Bohr’s magneton.