The linear charge density on a dielectric ring of radius R varies with θ as λ=λ0cos  θ/2, where λ0 is constant. Find the potential at the center O of the ring [in volt]

The charge on the infinitesimal elements of arc that subtends an angle dθ at the center of the ring is dQ=λRdθ=λ0cosθ2RdθPotential at the center of ring due to charge dQ is dV=14πε0dQR=λ0cosθ2.Rdθ4πε0Ror V=∫dV=λ04πε0∫02πcosθ2dθ=λ04πε0[sinθ212]02π=0  V