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Transcript
Electricity Electricity Everything in the world is made up of atoms. Each atom has smaller parts in it. One of those parts is called electrons. Electrons can move from atom to atom. When an electron moves to a different atom, it causes another electron to have to move. When electrons move quickly from one atom to another is it called Electricity! Inside an atom, electrons have a negative charge and protons have a positive A charge is a charge. These measure of the particles attract extra positive or negative particles each other. that an object has. Electricity occurs in 2 different forms Static • Is stationary E.g. Brush your hair Wool socks in tumble drier Current • Flows around circuit E.g. turn on light Walkman Static Electricity Static electricity is the charge that stays on an object. Unlike charges attract each other, and like charges repel each other. The steady flow of electricity is called an electric current. A current will move along a wire or a path called a circuit. Circuit means to “go around.” Any circuit which is not complete is considered an open circuit. A complete circuit which is not performing any actual work can still be a closed circuit. For example, a circuit connected to a dead battery may not perform any work, but it is still a closed circuit. A circuit is considered to be closed when electricity flows from an energy source to the desired endpoint of the circuit. The open status of the circuit doesn't depend on how it became unclosed, so circuits which are manually disconnected and circuits which have blown fuses, faulty wiring or missing components are all considered open circuits. Open circuit Closed circuit Circuits •A series circuit is a circuit that has only one path for the current. •A parallel circuit has more than one path for current to travel. SERIES CIRCUIT • Has a single loop for electrons to travel round • Components are connected one after another • Current has to travel through all components • Current is the same at all points • Voltage is shared between components PARALLEL CIRCUIT • Has two or more paths for electrons to flow down • Current is shared between the branches • Sum of the current in each branch = total current • Voltage loss is the same across all components SUMMARY In Series Current Always the same Voltage Voltage from source = voltage used Voltage is shared between power users In Parallel The branches share electrons and add to the total Voltage is the same in all branches •Lights in our homes are wired in parallel circuits. ELECTRICITY • Electricity is forced around a circuit by an electrical force field • Flow of electricity around a circuit is called CURRENT • Current measured in amps • Voltage – Increase or decrease in the amount of electrical energy carried by the current. CURRENT Current is the flow of electrons around a circuit •DC = direct current like battery •Electrons flow in one direction •AC = Alternating current like mains •Electron flow changes direction 50x per second Definition of AC •AC stands for "alternating current." The polarity of the electric charge switches from positive to negative, or alternates, at a fixed rate. For typical household current in the United States, the alternation rate is 60 cycles per second. Definition of DC •DC stands for "direct current." The polarity of the electric charge does not switch back and forth. This is why one end of a battery is positive, and the other end is negative. Current flows from the negative end of the battery, through the device being operated and back to the battery at the positive end. VOLTAGE Gain or loss of energy as it passes through a component •Voltage lost = voltage gained •In series voltage loss is shared between components •In parallel voltage loss is the same across all components Conductor •A conductor is a material that current can pass through easily, like metals. Resistor •A resistor is a material that resists, but doesn’t stop the flow of current. Insulator •An insulator is a material that current cannot pass through easily, like plastic. Electric Cell •An electric cell supplies energy to move charges through a circuit, like a battery.