Question

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 finite if'the current decreases at a steady rate

Answer 1

Answer: (A), (C)

Due to the current in the straight wire, net magnetic flux from
the circular loop is zero. Because in half of the circle
magnetic field is inwards and in other half, magnetic field is
outwards. Therefore, change in current will not cause any
change in magnetic flux from the loop. Therefore, induced
emf under all conditions through the circular loop is zero