A long straight wire carries a current of

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

Problem

3\,\text{A}

. The magnetic field at a point 4 cm from the wire is

B_1

. If the current is increased to

6\,\text{A}

and the observation point is moved to 8 cm from the wire, the new magnetic field

B_2

will be (a)

2B_1

(b)

4B_1

(c)

B_1

(d)

\dfrac{1}{2}B_1