JEE Mains · Physics · STD 12 - 4. Moving charges and magnetism
The dipole moment of a circular loop carrying a current \(I\), is \(m\) and the magnetic field at the centre of the loop is \(B_1\) . When the dipole moment is doubled by keeping the current constant, the magnetic field at the centre of the loop is \(B_2\) . The ratio \(\frac{{{B_1}}}{{{B_2}}}\) is
- A \(\sqrt 3 \)
- B \(\sqrt 2 \)
- C \(\frac{1}{{\sqrt 2 }}\)
- D \(2\)
Answer & Solution
Correct Answer
(B) \(\sqrt 2 \)
Step-by-step Solution
Detailed explanation
Magnetic field at the centre of \(\operatorname{loop}, B_{1}=\frac{\mu_{0} I}{2 R}\) Dipole moment of circular loop is \(m=I A\) \(\mathrm{m}_{1}=\mathrm{I} \cdot \mathrm{A}=\mathrm{I} \pi \mathrm{R}^{2} \quad\{\mathrm{R}=\text { Radius of the loop }\}\) If moment is doubled…
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