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QAIPMT-2005-Ph-2562: NEET 2005 Physics - Class 12 AIPMT-2005-Ph-2562 Solution: A coil in the shape of an equilateral triangle of side l is…

A coil in the shape of an equilateral triangle of side l is suspended between the pole pieces of a permanent magnet such that B⃗\vec{B} is in plane of the coil. If due to a current i in the triangle a torque τ\tau acts on it, the side l of the triangle is

Multiple Choice Options

  • A 23(τBi)\frac{2}{\sqrt{3}}\left(\frac{\tau}{Bi}\right)
  • B 2(τ3Bi)1/22\left(\frac{\tau}{\sqrt{3}Bi}\right)^{1/2}
  • C 23(τBi)1/2\frac{2}{\sqrt{3}}\left(\frac{\tau}{Bi}\right)^{1/2}
  • D 13τBi\frac{1}{\sqrt{3}}\frac{\tau}{Bi}

Step-by-Step Verified Solution

The current flowing clockwise in the equilateral triangle has a magnetic field in the direction k ^ . _ = BiNAsin _ = BiAsin90� _ A = _ i B Area of equilateral triangle A = 1 2 ( l ) l 2 _ ( l 2 ) 2 = 3 4 l 2 _ 3 4 l 2 = _ i B _ l = 2 ( _ 3 B i ) 1 2

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