未带电的矿粒在不均匀电场中受的力为: =ε_0R~3(ε_1-ε_2)/(ε_1+2ε_2)·grad式中R是矿粒的半径,ε_1是矿粒的介电常数,ε_2是浸没矿粒的另一种介质的介电常数,是矿粒所在处的电场强度,grad是矿粒所在处的电场梯度。本文介绍这个式子的—种推导过程。本文采用未有理化制的公式形式,为普遍起见,保留真空的介电常数ε_0而未把它写为1。 Uncharged mineral particles in the uneven electric field by the force: = ε_0R ~ 3 (ε_1-ε_2) / (ε_1 +2ε_2) · grad Where R is the radius of the mineral particles, ε_1 is the permittivity of the mineral particles, ε 2 is the dielectric constant of another medium immersed in the ore, which is the electric field strength where the ore is located and grad is the electric field gradient where the ore is located. This article describes a type of derivation of this formula. In this paper, an unphysical formula is adopted. For the sake of generality, the dielectric constant ε_0 of the vacuum is kept without writing it as 1.