JEE Mains · Physics · STD 12 - Moving charges and magnetism
- JEE Mains 2024
- Medium
- Numerical
A 2 A current carrying straight metal wire of resistance \(1 \Omega\), resistivity \(2 \times 10^{-6} \Omega m\), area of cross-section \(10 mm^2\) and mass 500 g is suspended horizontally in mid air by applying a uniform magnetic field \(\vec{B}\). The magnitude of \(B\) is _______ \(\times 10^{-1} T\) (given, \(g =10 m / s ^2\) ).
Pick an option to check your answer.
Answer & Solution
Correct Answer
(A) 5
Step-by-step Solution
Detailed explanation
\(R=\frac{\rho \ell}{A} \Rightarrow \frac{2 \times 10^{-6} \times \ell}{10^{-5}}=1 \Rightarrow \ell=5\)
\(mg = Bi \ell\)
\(B =\frac{ mg }{ i \ell}=\frac{5}{2 \times 5}=0.5=5 \times 10^{-1}\) Tesla
\(mg = Bi \ell\)
\(B =\frac{ mg }{ i \ell}=\frac{5}{2 \times 5}=0.5=5 \times 10^{-1}\) Tesla
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