Presentation on theme: "Electricity. Electrical Charge and Forces Electrical charge is the property that causes protons and electrons to attract or repel one another. There."— Presentation transcript:
Electrical Charge and Forces Electrical charge is the property that causes protons and electrons to attract or repel one another. There are electric charges in clothes that stick together from the dryer. The attraction or repulsion between electrical charges is called electric force. Like charges repel each other and opposite charges attract each other.
An electric field is the effect an electric charge has on other charges in the space around it. The strength of an electric field is dependant on 2 things. 1. amount of charge producing the field. 2. distance from the charge. The further the 2 charges are away from each other, the less force they feel. The closer the 2 charges are, the more force they feel.
Electric Field Lines Lines pointing in the direction of the electric field. Represent the strength and direction of the field. Electric field is stronger where lines are closer together. Lines point away from a positive charge and towards a negative charge.
Electric Materials There are 2 ways to describe whether a substance is able to conduct electricity. 1. Conductors – materials in which electric charges move easily. Copper, iron, and most other metals. 2. Insulators – materials in which electricity does not move easily. Glass, rubber, plastic.
Charge Transfer Static electricity is the study of the behavior of electric charges, including how it is transferred between objects. Charge can be transferred by: 1. friction. 2. contact. 3. induction.
Friction Rubbing a balloon on your head is an example of charging by friction. Electrons move from your hair to the balloon because the atoms in the balloon attract electrons much more strongly than the atoms in your hair. The balloon gets a negative charge and your hair gets a positive charge.
Contact A Van de Graaf generator charges a metal sphere and when you touch it you acquire a charge large enough to make your hair stand on end. The sphere is still charged, but its net charge is reduced.
Induction Induction is a transfer of charge without contact between materials. Ex: When you walk across the carpet your hand picks up a net negative charge. When you reach for a door knob, the negative charge of your hand causes the electrons in the doorknob to all move to the base of the doorknob. The doorknob still has a net charge of zero, but the charges have moved.
Homework Questions 1. What determines whether charges attract or repel? 2. Name 2 factors that affect the strength of an electric field. 3. List the 3 methods of charge transfer. 4. Explain and give an example of charging by friction. 5. When a glass rod is rubbed with silk, the glass becomes positively charged. What is the charge on the silk? Explain your answer.