Physics-
General
Easy

Question

When a circular coil of radius 1 m and 100 turns is rotated in a horizontal uniform magnetic field, the peak value of emf induced is 100 V. the coil is unwound and then rewound into a circular coil of radius 2 m. If it is rotated now, with the same speed, under similar conditions, the new peak value of emf developed is

  1. 50 V  
  2. 25 V  
  3. 100 V  
  4. 200 V  

The correct answer is: 200 V


    Induced EMF=fraction numerator N increment ϕ over denominator capital delta t end fraction
    Peak value =N B A omega equals 100 V …(i)
    Here blank 2 pi r subscript 1 end subscript cross times 100 equals 2 pi r subscript 2 end subscript cross times N subscript 2 end subscript
    N subscript 2 end subscript equals fraction numerator r subscript 1 end subscript cross times 100 over denominator r subscript 2 end subscript end fraction equals fraction numerator 1 cross times 100 over denominator 2 end fraction equals 50
    Now e subscript 0 end subscript equals fraction numerator N over denominator 2 end fraction cross times B cross times 4 A cross times omega equals 200 V.

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