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KVPY2020PhysicsElectrostatics

Consider a sphere of radius R with unform charged density and total charge Q . The electrostatic potential distribution inside the sphere is given by ϕ ( r ) = Q 4 π ε 0 R a + b ( r / R ) c . Note that the zero of potential is at infinity The values of ( a ,   b ,   c ) are:

Options

  1. A1 2 , - 3 2 , 1
  2. B3 2 , - 1 2 , 2
  3. C1 2 , 1 2 , 1
  4. D1 2 , - 1 2 , 2

Correct answer

B. 3 2 , - 1 2 , 2

Step-by-step solution

Potential inside uniformly charged solid sphere is given by V = k Q 2 R 3 3 R 2 - r 2 = k Q R 3 R 2 2 R 2 - r 2 2 R 2 = Q 4 π ∈ 0 R 3 2 - 1 2 r R 2 Compare with given formula, i.e, Q 4 π ∈ 0 R a + b r R C a = 3 2 ,   b = - 1 2 , c = 2

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