A charged particle of radius 5×10^−7 m is located in a horizontal electric field of intensity 6.28 × 10^5 V/m. The surrounding medium has the coeffiecient of viscosity η = 1.6 × 10^5 Ns/m^2. The particle starts moving under the effect of electric field and finally attains a uniform horizontal speed of 0.02 m/s. Find the number of electrons on it. Assume gravity free space.
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