AP EAMCET2006PhysicsMagnetic Effects of Current
Two short magnets A B and C D are in the X-Y plane and are parallel to X -axis and co-ordinates of their centres respectively are (0,2) and (2,0) . Line joining the north-south poles of C D is opposite to that of A B and lies along the positive X -axis. The resultant field induction due to A B and C D at a point P(2,2) is 100 10⁻⁷ ~T . When the poles of the magnet C D are reversed, the resultant field induction is 50
Options
- A300 ; 200
- B600 ; 400
- C200 ; 100
- D300 ; 150
Correct answer
A. 300 ; 200
Step-by-step solution
As shown in figure, B=B₁+B₂= ₀ 4 ( 2 M₁ r₁^3 + M₂ r₂^3 )100 10⁻⁷=10⁻⁷ ( 2 M₁ 8 + M₂ 8 ) 2 M₁+M₂=800 (i) If the poles of the magnet C D are reversed, then 50 10⁻⁷=10⁻⁷ ( 2 M₁ 8 - M₂ 8 ) 2 M₁-M₂=400 (ii) Solving Eqs. (i) and (ii), we obtain M₁=300 Am ^2, M₂=200 Am ^2