Question

An infintely long wire carrying current I is along y-axis such that its one end is at point A(0, b) while the wire extends upto + . The magnitude of magnetic field strength at point (a, 0).

• A. $\frac { \mu _ { 0 } \mathrm { I } } { 4 \pi \mathrm { a } } \left( 1 + \frac { \mathrm { b } } { \sqrt { \mathrm { a } ^ { 2 } + \mathrm { b } ^ { 2 } } } \right)$
• B. $\frac { \mu _ { 0 } \mathrm { I } } { 4 \pi \mathrm { a } } \left( 1 - \frac { \mathrm { b } } { \sqrt { \mathrm { a } ^ { 2 } + \mathrm { b } ^ { 2 } } } \right)$
• C. $\frac { \mu _ { 0 } \mathrm { I } } { 4 \pi \mathrm { a } } \left( \frac { \mathrm { b } } { \sqrt { \mathrm { a } ^ { 2 } + \mathrm { b } ^ { 2 } } } \right)$
• D. None of these

Answer 1

Answer: (B)

$\frac { \mu _ { 0 } \mathrm { I } } { 4 \pi \mathrm { a } } \left( 1 - \frac { \mathrm { b } } { \sqrt { \mathrm { a } ^ { 2 } + \mathrm { b } ^ { 2 } } } \right)$

Answer 2

B = $\frac { \mu _ { 0 } } { 4 \pi }$ $\frac { \mathbf { i } } { \mathrm { a } }$ (sin 90ŗ + sin(–q))

= $\frac { \mu _ { 0 } } { 4 \pi }$ $\left( 1 - \frac { b } { \sqrt { a ^ { 2 } + b ^ { 2 } } } \right)$