JEE Main20258 Apr 2025Evening ShiftPhysicsMagnetic Effects of CurrentActual
Figure shows a current carrying square loop ABCD of edge length is ' a ' lying in a plane. If the resistance of the A B C part is r and that of A D C part is 2 r , then the magnitude of the resultant magnetic field at centre of the square loop is
Options
- A3 ₀ I 2 a
- B₀ I 2 a
- C2 ₀ I 3 a
- D2 ₀ I 3 a
Correct answer
C. 2 ₀ I 3 a
Step-by-step solution
B = B _ AB + B _ BC + B _ CD + B _ DA aligned B = & [ - ₀(2 I / 3) 4 ( a / 2) 2 - ₀(2 I / 3) 4 ( a / 2) 2 . & .+ ₀( I / 3) 4 ( a / 2) 2 + ₀( I / 3) 4 ( a / 2) 2 ] k B = & [ -2 2 ₀ I 3 a + 2 ₀ I 3 a ] k B = & - 2 ₀ I 3 a k aligned