Charge and Current To make an electric circuit

Charge and Current

� 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.

� 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 �

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

� 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: 1. Series Circuit – All the electrons take the exact same path through the circuit

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

3. Combination Circuits – Has both series and parallel components.

� 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

� 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 � 1 = Charge/Time or Ampere = 1 Coulomb/s I = q/t

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

� Since �I I = q/t = 12/5 = 2. 4 Amperes or 2. 4 A

All circuit components are at the back of the room Instructions: 1. Work in Groups of 3 -4 2. Take the following back to your workspace Two batteries and cases � 10 wires � 4 lights (you can take motors too) � 4 switches 3. Begin by making a simple circuit and turning it on 4. Look at page 554 question #4 and try to make each circuit that is described. �