(a) When a positively charged object is brought near a neutral piece of paper, is the vector sum of the forces exerted by the charged object on the paper attractive or repulsive?

(b) Describe what would happen when a negatively charged comb is brought near an electroscope if protons, not electrons, were mobile in metals.

(c) Can you deduce from the experiment illustrated in Figure 22.19 which charge carrierselectrons or protons-are mobile in metals?

Figure 22.19 In (a) and (b), a charged rod induces polarization in an electroscope. (c) A schematic atom-level view. (a) (b) (c) Negative charge on rod repels electrons in metal. rod metal deficit of electrons (positive charge) surplus of electrons (negative 0 0 0 0 0 charge) positively charged free electron ion (fixed)