Moving Charges and Magnetism - Result Question 51

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52. At what distance from a long straight wire carrying a current of $12 A$ will the magnetic field be equal to $3 \times 10^{-5} Wb / m^{2}$ ?

======= ####52. At what distance from a long straight wire carrying a current of $12 A$ will the magnetic field be equal to $3 \times 10^{-5} Wb / m^{2}$ ?

3e0f7ab6f6a50373c3f2dbda6ca2533482a77bed:content/english/neet-pyq-chapterwise/physics/moving-charges-and-magnetism/moving-charges-and-magnetism—result-question-51.md (a) $8 \times 10^{-2} m$

(b) $12 \times 10^{-2} m$

(c) $18 \times 10^{-2} m$

(d) $24 \times 10^{-2} m$

[1995]

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Answer:

Correct Answer: 52. (a)

Solution:

  1. (a) Current (I) $=12 A$ and magnetic field (B) $=3 \times 10^{-5} Wb / m^{2}$. Consider magnetic field $\vec{B}$ at distance $r$.

Magnetic field, $B=\frac{\mu_0 I}{2 \pi r}$

$\Rightarrow r=\frac{\mu_0 I}{2 \pi B}=\frac{(4 \pi \times 10^{-7}) \times 12}{2 \times \pi \times(3 \times 10^{-5})}=8 \times 10^{-2} m$