- Magnetic dipole: A Magnetic Dipole consist of two unlike poles of equivalent strength and separated by a small distance.
- Magnetic moment: It is defined as the product of pole strength and the distance between the poles of a magnet.
⇒M=m×1where
M= magnetic moment,
m= pole strength and
I = distance between the poles
Given
L= length of wire and
M= magnetic moment of straight wire If
m = pole strength of magnetic wire then, the magnetic moment is
⇒M=m×LWhen the wire is bent into a semicircle of radius
r,
⇒L= circumference of the semicircle ⇒L=πr⇒r=Distance between the poles in the semicircular wire is
2r so,
⇒M′=m×2rwhere
M′ = magnetic moment of semicircular wire
By substituting the value of
r in the above equation, we get
⇒M′=By equation 1 and equation 2, we get
⇒M′=- Hence, option 1 is correct.