Question

20 amp current is flowing in a long straight wire. The intensity of magnetic field at a distance of 10 cm from the wire, will be:

• A. $ 4\times {{10}^{-5}}wb/{{m}^{2}} $
• B. $ 2\times {{10}^{-5}}wb/{{m}^{2}} $
• C. $ 3\times {{10}^{-5}}wb/{{m}^{2}} $
• D. $ 8\times {{10}^{-5}}wb/{{m}^{2}} $

Answer 1

Answer: (A)

Here: $ ~i=20 $ amp, $ r=10\text{ }cm=10\times {{10}^{-2}}m $ Intensity of magnetic field produced due to straight current carrying wire will be $ B=\frac{{{\mu }_{0}}}{4\pi }\times \frac{2i}{r} $ $ =\frac{{{10}^{-7}}\times 2\times 20}{0.1}=4\times {{10}^{-5}}\,wb/{{m}^{2}} $