Initially, a point is from a long straight wire carrying and the magnetic field there…

MATHEMATICS · Single correct · ISC · Physics · Magnetic Effects of Current and Magnetism · Ampere's circuital law

Problem

Initially, a point

P

2\,\text{cm}

from a long straight wire carrying

3\,\text{A}

and the magnetic field there is

B_0

. Later, the current is increased to

6\,\text{A}

and the point is moved to a distance of

6\,\text{cm}

. What is the ratio

\dfrac{B_{\text{new}}}{B_0}

? (a)

\dfrac{1}{3}

(b)

\dfrac{3}{2}

(c)

\dfrac{2}{3}

(d)

\dfrac{2}{9}