Question

A 200 turn closely wound circular coil of radius 15 cm carries a current 4 of A. The magnetic moment of this coil is

• A. $36.5 \mathrm {~A} \mathrm {~m} ^ { 2 }$
• B. $56.5 \mathrm {~A} \mathrm {~m} ^ { 2 }$ A
• C. $66.5 \mathrm {~A} \mathrm {~m} ^ { 2 }$
• D. $108 \mathrm {~A} \mathrm {~m} ^ { 2 }$

Answer 1

Answer: (B)

$56.5 \mathrm {~A} \mathrm {~m} ^ { 2 }$ A

Answer 2

The magnetic moment is given by

$= 200 \times 4 \times 3.14 \times \left( 15 \times 10 ^ { - 2 } \right) ^ { 2 }$

$= 200 \times 4 \times 3.14 \times 15 \times 15 \times 10 ^ { - 4 } = 56.5 \mathrm { Am } ^ { 2 }$