AP EAMCET202420 May 2024Evening ShiftPhysicsMagnetic Effects of CurrentActual
At a place where the magnitude of the earth's magnetic field is 4 10⁻⁵ ~T , a short bar magnet is placed with its axis perpendicular to the earth's magnetic field direction. If the resultant magnetic field at a point at a distance of 40 cm from the centre of the magnet on the normal bisector of the magnet is inclined at 45^ with the earth's field, then the magnetic moment of the magnet is
Options
- A38.4 Am ^2
- B51.2 Am ^2
- C12.8 Am ^2
- D25.6 Am ^2
Correct answer
D. 25.6 Am ^2
Step-by-step solution
B _ e =4 10⁻⁵ ~T , r =40 ~cm Magnetic field at a point on the normal bisector of the magnetic is aligned & B = ₀ 4 M r ^3 & 45^ = B _ e ~B ~B _ e = B & ~B _ e = ₀ 4 M r ^3 M = B _ e ^3 r ^3 ₀ 4 & M = 4 10⁻⁵ (0.4)^3 10⁻⁷ =25.6 Am ^2 aligned