Magnetic Effects of Current & Magnetism · JEE Main previous year questions

2004 3 questions

1. Q1192004 · 24 Apr 2004 · Shift 1

   A long wire carries a steady current. It is bent into a circle of one turn and the magnetic field at the centre of the coil is $B$. It is then bent into a circular loop of $n$ turns. The magnetic field at the center of the coil will be

   1. A.$2nB$
   2. B.$n^{2}B$
   3. C.$nB$
   4. D.$2n^{2}B$
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   Answer: B

2. Q1202004 · 24 Apr 2004 · Shift 1

   The magnetic field due to a current carrying circular loop of radius $3\mathrm{cm}$ at a point on the axis at a distance of $4\mathrm{cm}$ from the centre is $54\mu \mathrm{T}$. What will be its value at the center of loop?

   1. A.$125\mu \mathrm{T}$
   2. B.$150\mu \mathrm{T}$
   3. C.$250\mu \mathrm{T}$
   4. D.$75\mu \mathrm{T}$
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   Answer: C

3. Q1292004 · 24 Apr 2004 · Shift 1

   A metal conductor of length $1\mathrm{m}$ rotates vertically about one of its ends at angular velocity $5$ radians per second. If the horizontal component of earth's magnetic field is $0.2\times 10^{-4}\mathrm{T}$, then the $e.m.f.$ developed between the two ends of the conductor is

   1. A.$5\mathrm{mV}$
   2. B.$50\mu \mathrm{V}$
   3. C.$5\mu \mathrm{V}$
   4. D.$50\mathrm{mV}$
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   Answer: B