Concepts Of Physics MCQ Edition [Volume 2]PhysicsMagnetic Field due to a Current
A transmission wire positioned 8 m above a road carries a current of 100 A . Determine the magnetic field B at a point on the road.
Options
- A1.25 10⁻⁶ T
- B5.0 10⁻⁶ T
- C2.5 10⁻⁶ T
- D2.5 10⁻⁵ T
Correct answer
C. 2.5 10⁻⁶ T
Step-by-step solution
The magnetic field due to a long straight wire at a perpendicular distance r is given by B = ₀ I 2 r . Given I = 100 A and r = 8 m . Substituting the values: B = 4 10⁻⁷ 100 2 8 B = 2 10⁻⁵ 8 B = 0.25 10⁻⁵ T B = 2.5 10⁻⁶ T