Field at center of ring (z = 0): Bz = µ0I. 2R. ⢠Magnetic moment: µ = IÏR. 2. ⢠Field at large distance (z â« R) : Bz â. µ0. 2Ï. µ z3. 28/3/2011. [tsl214 â 6/14]
Magnetic Field of Circular Current • Law of Biot and Savart: dB = • dBz = dB sin θ = dB √
µ0 Idℓ 4π z 2 + R2
R
z 2 + R2 Rdℓ µ0 I ⇒ dBz = 4π (z 2 + R2 )3/2 Z 2πR R µ0 I dℓ • Bz = 4π (z 2 + R2 )3/2 0 R2 µ0 I ⇒ Bz = 2 (z 2 + R2 )3/2 • Field at center of ring (z = 0): Bz =
µ0 I 2R
• Magnetic moment: µ = IπR2 • Field at large distance (z ≫ R) : Bz ≃
