JEE Main2013PhysicsMagnetic Properties of MatterActual
Two short bar magnets of length 1 cm each have magnetic moments 1 .20 A m 2 and 1 .00 A m 2 respectively. They are placed on a horizontal table parallel to each other with their N poles pointing towards the south. They have a common magnetic equator and are separated by a distance of 20 .0 cm . The value of the resultant horizontal magnetic induction at the mid-point O of the line joining their centres is close to (
Options
- A3 .50 × 10 - 4   Wb   m - 2
- B5 .80 × 10 - 4     Wb   m - 2
- C3 .6 × 10 - 5     Wb   m - 2
- D2 .56 × 10 - 4   Wb   m - 2
Correct answer
D. 2 .56 × 10 - 4   Wb   m - 2
Step-by-step solution
B net = B 1 + B 2 + B H = μ 0 4 π M 1 x 3 + μ 0 4 π M 2 x 3 + B H = 10 − 7 ( 1.2 + 1 ) ( 0.1 ) 3 + 3.6 × 10 − 5 = 2.56 × 10 - 4 Wb / m 2