Question

a current 10A flows downwards a in a long straight vertical conductor and the earth's horiz is 2 x 10- 7 T . Then the neutral point occurs

Answer 1

Explanation:

Given a current 10A flows downwards a in a long straight vertical conductor and the earth's horizontal  is 2 x 10- 7 T . Then the neutral point occurs  

•     Magnetic field due to infinite wire is μoI / 2π r
•  We have at neutral point net magnetic field is zero
• Therefore we have magnetic field due to wire is equal to magnetic field due to earth.
• So I = 10 A
• So we get  Magnetic field will be
•   Substituting the values we get   2 x 10^-7 = μo x 10 / 2 π r
•                 2 πr x 10^-7 = 5 μo
•                Or r = 5 μo / 2π x 10^-7
•                Or r = 5 x 4π x 10^-7 / 2π x 10^-7
•                Or r = 10 m
• Magnetic field due to wire will be moving against the magnetic field due to earth in the east direction and hence both will cancel each other.

Reference link will be

https://brainly.in/question/23296041

Answer 2

Answer:

r=10m will be the correct answer