Question 273Electricity & Electronics - QMED

The correct answer is B) a canvas wiper. To effectively clean a commutator in good physical condition, a canvas wiper should be used. This is the recommended method as it is a soft, abrasive-free material that can gently clean the commutator surface without causing any damage. The other options are not suitable - trichloride ethylene is a harsh chemical that can damage the commutator, kerosene is also a strong solvent that could remove the commutator's protective coating, and a commutator stone is too abrasive and can leave scratches on the surface.