1. 17.3 Applications and hazards of electrostatics Spraying pesticidesExample 2 Farmers sometimes use aircraft to spray pesticides onto the crops in large crop fields. The pesticides are positively charged when they are ejected from the spray gun. The droplets of pesticides are then attracted by the soil and plants.

2. 17.3 Applications and hazards of electrostatics  The positively charged droplets of pesticide induce negative charges on the upper surface of the soil and plants.  An attractive force is induced between charges. (a) Explain why there is an attractive force.

3. 17.3 Applications and hazards of electrostatics (b) What are the possible disadvantages if the pesticides are not charged.  The electrostatic attractive force would not exist.  More pesticides are needed to compensate the loss.  The pesticides blown away may bring harmful effects to living things.