Magnetic Effects & Magnetism

JEE Main level, numerical answer, medium

7 of 276

Question 7 of 276

A closely wounded circular coil of radius 5cm5cm produces a magnetic field of 37.68×10−4T37.68\times {10}^{-4}T at its center. The current through the coil is _____ AA. [Given, number of turns in the coil is 100100 and π=3.14\pi =3.14]

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Answer: 3

Given here, N=100N=100, R=5cmR=5cm and B=37.68×10−4TB=37.68\times {10}^{-4}T
Magnetic field at the centre of circular coil is given by Bcentre=Nμ0l2R{B}_{centre}=\dfrac{N{\mu }_{0}l}{2R}.
Putting the values,
37.68×10−4=100×4π×10−7×I2×5×10−237.68\times {10}^{-4}=\dfrac{100\times 4\pi \times {10}^{-7}\times I}{2\times 5\times {10}^{-2}}
Current through coil is I=3AI=3A.

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