When a scientist wipes a rubber rod with a wool cloth, it results in the transfer of electrons from the wool cloth to the rubber rod. This transfer of electrons causes the rubber rod to gain extra electrons, resulting in an excess negative charge on the rod. The wool cloth loses some electrons and thus becomes positively charged or has a deficiency of electrons. This phenomenon is known as triboelectric charging, where two materials become electrically charged due to friction and the transfer of electrons.
