COMEDK2025PhysicsMagnetic Effects of CurrentActual
A straight wire carrying current of 21 A is bent into an arc of radius 11 cm as shown below. The magnetic field produced by the current at the centre O of the arc is:
Options
- A3.0 10⁻⁴ ~T
- B3.0 10⁻³ ~T
- C0.3 10⁻⁵ ~T
- D0.3 10⁻⁴ ~T
Correct answer
D. 0.3 10⁻⁴ ~T
Step-by-step solution
The straight segments pass through centre O , so they produce no magnetic field at O . The arc is a quarter circle, so = 2 B = ₀ I 4 r = ₀ I 4 r 2 = ₀ I 8r B = 4 10⁻⁷ 21 8 0.11 = 4 22 7 3 10⁻⁷ 0.88 = 264 10⁻⁷ 0.88 B = 300 10⁻⁷ = 0.3 10⁻⁴ T