JEE Advanced · Physics · 21. EMI
A current carrying infinitely long wire is kept along the diameter of a circular wire loop, without touching it, the correct statement(s) is(are)
- A The emf induced in the loop is zero if the current is constant.
- B The emf induced in the loop is finite if the current is constant.
- C The emf induced in the loop is zero if the current decreases at a steady rate.
- D The emf induced in the loop is infinite if the current decreases at a steady rate.
Answer & Solution
Correct Answer
(C) The emf induced in the loop is zero if the current decreases at a steady rate.
Step-by-step Solution
Detailed explanation
If the current is constant, the emf induced in the loop zero. Emf will be induced in the circular wire loop when flux through it changes with time.
\(\mathrm{e}=-\frac{\Delta \phi}{\Delta \mathrm{t}}\)
when the current is constant, the flux changing through it will be zero.
Also, if the current decreases at steady rate, the emf. induced in the loop is zero.
When the current is decreasing at a steady rate then the change in the flux (decreasing inwards) on the right half of the wire is equal to the change in flux (decreasing outwards) on the left half of the wire such that \(\Delta \phi\) through the circular loop is zero.

\(\mathrm{e}=-\frac{\Delta \phi}{\Delta \mathrm{t}}\)
when the current is constant, the flux changing through it will be zero.
Also, if the current decreases at steady rate, the emf. induced in the loop is zero.
When the current is decreasing at a steady rate then the change in the flux (decreasing inwards) on the right half of the wire is equal to the change in flux (decreasing outwards) on the left half of the wire such that \(\Delta \phi\) through the circular loop is zero.

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