Fractional cumulative yields (FCY) of various light mass fission products in the ²³³U(n_th, f), ²³⁵U(n_th, f) and ²³⁹Pu (n_th, f) reactions were measured by using an off-line γ-ray spectrometric technique. The values of most probable charge (Z_P) were obtained by using the width of isobaric charge distribution (σ_Z) of nearby fissioning systems with proper apportion. From the Z_P values, the experimental charge polarization (ΔΖ_EXPT) as a function of fragment mass were also deduced. The ΔΖ_EXPT values for the light mass chains from the present work and for the heavy mass chains from earlier work show an oscillating nature in the interval of five mass units due to even-odd staggering. A local effect around the shell region and a systematic decreasing trend with the approach of symmetric split was also observed. The ΔΖ_MPE values based on minimum potential energy surface were theoretically calculated, which shows no oscillation but only a systematic decreasing trend with the approach of symmetric split due to the assumption of liquid drop behaviour of the fissioning nucleus.