JEE Mains · Physics · STD 12 - 4. Moving charges and magnetism
Consider two thin identical conducting wires covered with very thin insulating material. One of the wires is bent into a loop and produces magnetic field \(B_1,\) at its centre when a current \(I\) passes through it.The second wire is bent into a coil with three identical loops adjacent to each other and produces magnetic field \(B_2\) at the centre of the loops when current \(I/3\) passes through it. The ratio \(B_1 : B_2\) is
- A \(1:1\)
- B \(1:3\)
- C \(1:9\)
- D \(9:1\)
Answer & Solution
Correct Answer
(B) \(1:3\)
Step-by-step Solution
Detailed explanation
For loop \(\mathrm{B}=\frac{\mu_{0} \mathrm{nI}}{2 \mathrm{a}}\) where, \(a\) is the radius of loop. Then, \(B_{1}=\frac{\mu_{0} I}{2 a}\) Now, for coil \(\mathrm{B}=\frac{\mu_{0} \mathrm{I}}{4 \pi} \cdot \frac{2 \mathrm{nA}}{\mathrm{x}^{3}}\) at the centre \(x=\) radius of loop…
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