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A uniform current I is flowing in a long...

A uniform current `I` is flowing in a long wire of radius `R`. If the current is uniformly distributed across the cross-sectional area of the wire, then

A

magnetic field inside the cylinder increases linearly from zero at the centre

B

magnetic field will be maximum at a point on its axis

C

magnetic field will be maximum at a point on its surface

D

magnetic field is minimum at a point on its surface

Text Solution

Verified by Experts

The correct Answer is:
a, c
Magnetic field intensity due to this system at a point at a distance from its centre is given as follows:
` x lt R : B = (mu_(0) I x)/(2 pi R^(2))`
` x gt R : B = (mu_(0)i)/(2 pi x)`
Hence magnetic field is zero at x = 0 and option (a) is correct.
Magnetic field is increasing linearly from the centre up to the surface and then further, it decreases inversely proportional to the distance, hence it attains a maximum field at the surface. Thus, option (c) is also correct.
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Knowledge Check

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