An electric current passes through a long straight copper wire. At a perpendicular distance 5 cm from the straight wire, the magnetic field is B. The magnetic field at perpendicular distance 20 cm from the straight wire would be
The correct answer is (B) B/4.
The magnetic field due to a long straight current-carrying wire is given by
B ∝ 1/r. If the distance is increased from 5 cm to 20 cm (4 times), the magnetic field decreases by 4 times, becoming B/4.
Share
The magnetic field due to a long straight current-carrying wire is given by:
B = μ0I/2πr
Here, B ∝ 1/r .
If the distance increases from 5 cm to 20 cm (i.e., four times), the magnetic field decreases by the same factor:
B′ = B/4.
Therefore, the new magnetic field is B/4.
Answer: (B) B/4.
For more visit here:
https://www.tiwariacademy.com/ncert-solutions/class-12/physics/chapter-4/