Electric charges and field

 

Electric Charges and Fields

  
 Problems

Question1.A charged spherical conductor has a surface density of 0.7 Cm^-2. When its change is increased by 0.44 C, the charge density changes by 0.14 Cm^-2. Find the radius of the sphere and initial charge on it.

 Solution. The spherical charged conductor has surface density

Question4. A charge is distributed uniformly over a ring of radius ‘a’. Obtain an expression for the electric intensity ‘E’ at a point on the axis of the ring. Hence show that for the points at a large distance from the ring, it behaves like a point charge.  

Solution. Suppose that the ring is placed with its plane perpendicular to the x-axis. Consider a small element dl of the ring.

As the total charge q is uniformly distributed, the charge dq on the element dl is

 

Question5. A thin semicircular ring of radius ‘a’ is charged uniformly and the charge per unit length is ‘λ’. Find the electric field at its center.