Physics-
General
Easy

Question

A bar magnet of length 3 cm has points A and B along its axis at distances of 24 cm and 48 cm on the opposite sides. Ratio of magnetic fields at these points will be

  1. 8    
  2. 1 divided by 2 square root of 2    
  3. 3    
  4. 4    

The correct answer is: 8


    Both points A and B lying on the axis of the magnet and on axial position
    B proportional to fraction numerator 1 over denominator d to the power of 3 end exponent end fraction Þ fraction numerator B subscript A end subscript over denominator B subscript B end subscript end fraction equals open parentheses fraction numerator d subscript B end subscript over denominator d subscript A end subscript end fraction close parentheses to the power of 3 end exponent equals open parentheses fraction numerator 48 over denominator 24 end fraction close parentheses to the power of 3 end exponent equals fraction numerator 8 over denominator 1 end fraction

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