As shown in the figure, next to an uncharged metal ball with a radius of R, a point charge with an electric quantity of Q is placed, and the point charge is far from the center of the ball.

Point o is a point in a conductor whose electric field strength is zero. According to the superposition principle of electric field intensity, the electric field at point O is generated by point charge Q and induced charge on the ball. Therefore, the electric field intensity generated by the induced charge on the ball at point O is equal to the electric field intensity generated by point charge Q at point O. ..

Extended data:

Analysis: The metal ball A is in the electric field formed by point charge B, reaching electrostatic balance, and the resultant field strength at the center of ball O is zero, that is, the field strength generated by point charge B at any point in the ball is equal to the charge on ball A (the charge carried by metal ball A and the induced charge), and the direction is opposite. The electric field intensity generated by point charge B at point O is E=kq/r2, so the electric field intensity generated by the charge on metal ball A at the center of ball O is equal to E'=E=kq/r2.

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