Electric circuits Charge and Current

Electric Circuits To make an electric circuit, we have to get electrons to travel in a continuous circle through a device that can change their energy. For example, a light bulb is something that can turn the moving (kinetic) energy of the electrons into light.

Components of a Circuit Circuits can be very complicated with many devices designed to control and direct the flow of elelctrons but a simple circuit only requires the following Power Source – Something that creates a source of free electrons (e.g. a battery) Wires – To conduct the electrons around the circuit Load – A device that converts the energy of electrons into something useful (e.g. a light bulb or heating coil) Switch – Something that allows us to break the circuit and stop the flow of electrons

Components of a circuit

Drawing Circuits Power Source Wires Load Switch When electricians plan electric circuits they use symbols to represent the parts Power Source Wires Load Switch

Types of circuits Some circuits are very simple and some are very complicated with many loads, switches wires and power sources. But circuits can be divided into three basic types: Series Circuit – All the electrons take the exact same path through the circuit

Types of circuits Parallel Circuit – All the electrons start at the same place and finish at the same place but can take different paths

Types of circuits 3. Combination Circuits – Has both series and parallel components.

Electric Charge Charge (q) is a measurement of the number of electrons. Electrons are very small so it is impossible to count the exact number that are going through a circuit. Instead, scientists (and electricians) measure charge in Coulombs. Think of a Coulomb as a huge pile of electrons. 1 Coulomb = 6.24150934 × 1018 electrons

Electric current Electrons move quickly through a circuit Current (I) is a measurement of the speed that the electrons are moving. Current is measured in Amperes. Think of current as the number of electrons that pass a certain point in the circuit each second Current = Charge/Time or I = q/t 1 Ampere = 1 Coulomb/s

Learning Check If 12 Coulombs of charge pass through a point in a circuit every 5 seconds, what is the current?

Learning check Since I = q/t I = 12/5 = 2.4 Amperes or 2.4 A

Exploration activity All circuit components are at the back of the room Instructions: Work in Groups of 3-4 Take the following back to your workspace Two batteries and cases 10 wires 4 lights (you can take motors too) 4 switches Begin by making a simple circuit and turning it on Look at page 554 question #4 and try to make each circuit that is described.