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Electric Charges And Fields

Question

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

2×10^-5 Wb/m²

9×10^-5 Wb/m²

4×10^-5 Wb/m²

6×10^-5 Wb/m²

Solution

4×10^-5 Wb/m²

Here :- i=20A, r=10cm=0.1m

Intensiy of magnetic field produced due to straight current carrying wire is

$B = \frac{μ_{o}}{4 π} \times \frac{2 i}{r} = 10^{- 7} \times \frac{2 \times 20}{0.1} = 4 \times 10^{- 3} Wb / m^{2}$