CameraIcon
CameraIcon
SearchIcon
MyQuestionIcon
MyQuestionIcon
1
You visited us 1 times! Enjoying our articles? Unlock Full Access!
Question

A long straight wire of radius a carries a steady current I. The current is uniformly distributed over its cross-section. The ratio o the magnetic fields B and B, at radial distances a2 and 2a respectively, from the axis of the wire is

A
14
No worries! We‘ve got your back. Try BYJU‘S free classes today!
B
12
No worries! We‘ve got your back. Try BYJU‘S free classes today!
C
1
Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses
D
4
No worries! We‘ve got your back. Try BYJU‘S free classes today!
Open in App
Solution

The correct option is A 1
Consider two amperian loops of radius a/2 and 2a as shown in the diagram.
Applying ampere's circuital law for these loops, we get
B.dL=μ0Ienclosed
For the smaller loop,
B×2πa2=μ0×1πa2×(a2)2
=μ0I×14=μ0I4
B1=μ0I4πa
B×2π(2a)=μ0I
BB=μ0I4πa×4πaμ0I=1
Hence,
option (C) is correct answer.

flag
Suggest Corrections
thumbs-up
0
Join BYJU'S Learning Program
similar_icon
Related Videos
thumbnail
lock
The Net Flow of Charge
PHYSICS
Watch in App
Join BYJU'S Learning Program
CrossIcon