* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download File
Power engineering wikipedia , lookup
Ground loop (electricity) wikipedia , lookup
Printed circuit board wikipedia , lookup
Mercury-arc valve wikipedia , lookup
History of electric power transmission wikipedia , lookup
Voltage optimisation wikipedia , lookup
Electrical ballast wikipedia , lookup
Ground (electricity) wikipedia , lookup
Switched-mode power supply wikipedia , lookup
Fault tolerance wikipedia , lookup
Flexible electronics wikipedia , lookup
Stray voltage wikipedia , lookup
Resistive opto-isolator wikipedia , lookup
Electrical substation wikipedia , lookup
Two-port network wikipedia , lookup
Surface-mount technology wikipedia , lookup
Buck converter wikipedia , lookup
Regenerative circuit wikipedia , lookup
Opto-isolator wikipedia , lookup
Current source wikipedia , lookup
Integrated circuit wikipedia , lookup
Mains electricity wikipedia , lookup
Alternating current wikipedia , lookup
Surge protector wikipedia , lookup
Rectiverter wikipedia , lookup
Earthing system wikipedia , lookup
Circuit breaker wikipedia , lookup
Electrical wiring in the United Kingdom wikipedia , lookup
A circuit is like a central heating system in a house: low pressure Boiler and pump radiator flow of water There is a pump that High pressure pushes water round the system. The water everywhere starts to move AT THE SAME TIME. There are pipes that CARRY the water. In the pipes the water is FLOWING. © Boardworks Ltd 2003 An electrical circuit is very similar to a central heating system. The __ __ in the circuit is like a radiator. An electrical device uses electrical energy supplied by the circuit. Instead of a flow of water, electricity flows in an electrical circuit. The _______ are like pipes; they carry the electricity (called current) round the circuit. The electrical current is pushed by the _______, which has the same function as the pump and boiler. The strength of push provided by the battery is called its voltage. © Boardworks Ltd 2003 Series circuit This is a simple series circuit. In a simple series circuit, everything is connected in one loop across the terminals of the battery. So there AREN’T any points where the current can split or join (these are called junctions). This circuit has two lamps connected in series. Circuits are always drawn using straight lines. lamps © Boardworks Ltd 2003 Parallel circuits A B A parallel circuit is one which contains a point (a junction) where the current can SPLIT (point A) or JOIN (point B). This means that there is MORE than one path around the circuit. © Boardworks Ltd 2003 Series circuit Here are some other simple series circuits: 1. Two resistances (resistors) connected in series. R1 R2 2. A rheostat (or variable resistor) and a bulb connected in series. © Boardworks Ltd 2003 Measuring voltage - across a resistance or a bulb A Components component here R V Voltage is measured by connecting the voltmeter V across (or in parallel with) the component. Voltage is measured in volts and the symbol for this is V. © Boardworks Ltd 2003 Circuit 1 V Circuit2 Circuit2 V R1 R1 R2 V V1 V2 The _______ is the amount of push. When two components were put into Circuit 2, the voltage of the supply was the ____ as Circuit 1. However, the voltage across R1 ________ . The voltage across both components in circuit 2 added to be equal to the _____ voltage. supply, decreased, voltage, flow, same © Boardworks Ltd 2003 REMEMBER: The voltage supplied by the battery is shared between all the components in a series circuit. V(supply) = V1 + V2 The voltage supplied by the battery is stays the same for all the components in a parallel circuit. V(supply) = V1 = V2 = V3 © Boardworks Ltd 2003 Measuring current The unit of measure for current is the "amp" which has the symbol A. We measure the current using a device called an ammeter. In a circuit this is given the symbol A When measuring the current through a component, the ammeter is always connected in series (in the same loop) with that component. A © Boardworks Ltd 2003 Experiment: measuring current Circuit 1 1 A R1 A 2 1. Set up the circuit as shown above. 2. Measure the current using the ammeter at positions 1 and 2. © Boardworks Ltd 2003 Experiment: measuring current Circuit 2 1 A A R1 A 3 R2 2 1. Add another resistor into the circuit. 2. Now measure the current using the ammeter at positions 1, 2 and 3. © Boardworks Ltd 2003 Conclusions Circuit 1 The current at different positions in the circuit, before and after the resistor, was the _____. Current is ___ used up by the components in the circuit. Circuit 2 Increasing the number of components in the circuit _______ the current. The current at all points in a series circuit is the ____. same / same / decreased / not © Boardworks Ltd 2003 Measuring current in parallel circuits 1 A1 A2 2 A4 4 A3 3 Ammeter A1 A2 Current (A) 1. Place the ammeter, in turn, at positions 1, 2, 3 and 4. 2. Record the ammeter reading at the points in the table shown. A3 A4 © Boardworks Ltd 2003 For a parallel circuit, the current that leaves the cell or battery is the same as the current that returns to the cell or battery. The current does NOT get used up by a circuit, just the energy the electrons are carrying. A1 = A4 The current splits up at the first junction and then joins together at the second junction. If the bulbs are identical then the current will split evenly. If the bulbs are NOT identical, then the current will NOT split evenly. The following is always true for this circuit. A1 = A2 + A3 =A4 © Boardworks Ltd 2003 REMEMBER: In a series circuit the current is the same at any point in the circuit. A1 = A2 = A3 In a parallel circuit the current is being split up at the first junction and then joins together at the second junction.. A1 = A2 + A3 =A4 © Boardworks Ltd 2003 Summary for series circuits 1. In a series circuit the current is the same at any point in the circuit. 2. The supply voltage is shared between the components in a series circuit. 3. The current depends on the voltage in ANY circuit. © Boardworks Ltd 2003