Question

A large metal sheet carries an electric current along its surface. Current per unit length is l. Magnetic field near the metal sheet is–

• A. $\frac { 1 } { 2 } \mu _ { 0 } \lambda$
• B. $\frac { \lambda \mu _ { 0 } } { 2 \pi }$
• C. l m₀
• D. $\frac { \mu _ { 0 } } { 2 \lambda \pi }$

Answer 1

Answer: (A)

$\frac { 1 } { 2 } \mu _ { 0 } \lambda$

Answer 2

Applying Ampere's law

$\oint \overrightarrow { \mathrm { B } } \cdot \overrightarrow { \mathrm { d } \ell }$ = m₀(ll) 2Bl = m₀ll

B = $\frac { 1 } { 2 } \mu _ { 0 } \lambda$