# a long straight wire of circular cross section of radius a carries a steady current i. the current is uniformly distributed across its cross section. the ratio of the magnitudes of magnetic field at a point distant a/2 above the surface of wire to that at a point distant a/2 below its surface is

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get a long straight wire of circular cross section of radius a carries a steady current i. the current is uniformly distributed across its cross section. the ratio of the magnitudes of magnetic field at a point distant a/2 above the surface of wire to that at a point distant a/2 below its surface is from screen.

## A long straight wire of radius a carries a steady current. The current is uniformly distributed across its cross

Click here👆to get an answer to your question ✍️ A long straight wire of radius a carries a steady current. The current is uniformly distributed across its cross - section.the ratio of the magnetic field at a/4 inside and a/4 outside from the surface of wire is:

A long straight wire of radius a carries a steady current. The current is uniformly distributed across its cross-section.the ratio of the magnetic field atQuestion 4 a inside and 4 a

outside from the surface of wire is:

**A**

## 1:1

**B**

## 7:16

**C**

## 15:16

**D**

## 16:9

Easy Open in App

Updated on : 2022-09-05

Solution Verified by Toppr

Correct option is C)

Solution :We know,magnetic field B in inside points =

2πR 2 μ 0 ir

[where,R = radius,r = distance of the inside point from the axis and i = total current]

Distance from the axis at

4 a inside = (a− 4 a ) = 4 3a

So,Magnetic field at

4 a inside = 2πa 2 μ 0 ×i× 4 3a = 8πa 3μ 0 i

Distance from the axis at

4 a outside = (a+ 4 a )

We also know,magnetic field B at outside points =

2πr μ 0 i

[r=distance of the outside point from the axis]

So,magnetic field at

4 a outside = 2π× 4 5a μ 0 i = 5πa 2μ 0 i

The ratio of the magnetic field at

4 a inside and 4 a

outside the surface of the wire =

5πa 2μ 0 i 8πa 3μ 0 i =15:16

So,the correct option is C.

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## A long straight wire of a circular cross section (radius a) carries a steady current 7 and the current / is uniformly distributed across this cross

Magnetic field due to a long straight wire of radius a carrying current I at a point distance r from the centre of the wire is given as follows: B=(mu(0)ir)/(2pia^(2))" " for r < a B=(mu(0)ir)/(2pia^(2)) " " for r=a B=(mu(0)ir)/(2pia^(2)) " " for r gt a The variation of magnetic field B with distance r from the centre of wire is shown in the figure.

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Magnetic Effects Of Current And Magnetism

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A long straight wire of a circ...

A long straight wire of a circular cross section (radius a) carries a steady current 7 and the current / is uniformly distributed across this cross-section. Which of the following plots represents the variation of magnitude of magnetic field B with distance from the centre of the wire?

Text Solution Open Answer in App A B C D Answer

The correct Answer is A

Solution

Magnetic field due to a long straight wire of radius a carrying current I at a point distance r from the centre of the wire is given as follows:

forrB= μ 0 ir 2π a 2

B=μ0ir2πa2 forrB= μ 0 ir 2π a 2 forr=a B=μ0ir2πa2 forr=a B= μ 0 ir 2π a 2 forr>a B=μ0ir2πa2 forr>a

The variation of magnetic field B with distance r from the centre of wire is shown in the figure.

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