Question

5. A long straight wire carries an electric current
of 2 A. The magnetic induction at a
perpendicular distance of 5 m from the wire is
(A) 4 x 10-8 T (B) 8 x 10-T
(C) 12 x 10-T (D) 16 x 10-T
581​

Answer 1

Given Information,

• Current (l) = 2A
• Perpendicular Distance (d) = 5m
• Permeability = 4π × 10^-7 H/m

Magnetic Induction along a straight line is given as :

$\star \: \boxed{ \boxed{B = \dfrac{ \mu_o i}{2\pi r} }}$

Substituting values,

$\longrightarrow B = \dfrac{ 4\pi \times {10}^{ - 7} \times 2}{2\pi \times 5} \\ \\ \longrightarrow B = \dfrac{ 2 \times 2 \times {10}^{ - 7} }{ 5} \\ \\ \longrightarrow B = \dfrac{4}{5} \times {10}^{ - 7} \\ \\ \longrightarrow \boxed{ \boxed{B =8 \times {10}^{ - 8} \: T }}$

Option (b) is correct.