Question
19) Rice Krispies are very lightweight and electrically neutral. If a negatively charged rod is placed in with the puffs. they will be attracted to the rod. However, after a short period of time they fly off in all directions. Why does this happen? [2 marks]
Solution
4
(183 Votes)
Collins
Professional ยท Tutor for 6 years
Answer
The Rice Krispies are initially attracted to the negatively charged rod due to **polarization**. The negative charge on the rod repels the electrons in the Rice Krispies, causing a slight positive charge to develop on the side of the Krispies closest to the rod. This induced positive charge is attracted to the negative rod.However, once the Rice Krispies touch the rod, some of the excess electrons on the rod transfer to the Krispies, giving them a net negative charge. Since like charges repel, the now negatively charged Rice Krispies are repelled away from the similarly negatively charged rod, causing them to fly off.