A charge Q is uniformly distributed only on three fourths portion of a ring of radius R. The electric potential at centre of ring is    

Electrostatics: Potential at the Center of a Partially Charged Ring

Solution:

• Potential at the center of a fully charged ring: 
  V_{full ring} = (1 / 4πε₀) × (Q / R)
• For charge distributed over only 3/4^th of the ring, the potential is proportional to the fraction of the ring:
• V = (3Q) / (16 π ε₀ R)

Final Answer:

The electric potential at the center is:
V = (3Q) / (16πε₀R)