A thin rod of length L is magnetized and has magnetic moment M . The rod is then bent in a semicircular arc.…

A thin rod of length L is magnetized and has magnetic moment M. The rod is then bent in a semicircular arc. The magnetic moment in the new shape is
  1. ML
  2. Mπ
  3. M2π
  4. 2Mπ

Solution

Length of arc 

L=πR

⇒R=Lπ       ...1

Magnetic moment of rod M=mL   ...2

Magnetic moment of semicircular arc 

Marc=m2R

⇒Marc=m2Lπ

⇒Marc=2πmL

⇒Marc=2πM

Asked in: AP EAMCET 2020 (23 Sep Shift 1)

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