The torque is calculated on an electrically resistive rotating cylinder and sphere through which a current is fed by means of sliding contacts. The torque on a rotating cylinder is proven to vanish identically for arbitrary angular velocity. The torque on the sphere is shown to vanish up to second order in an expansion with the angular velocity as the expansion parameter. The nonzero torque in first order found by Gruenberg is shown to be due to an algebraic error.
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