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Transcript
Year 10 Science Revision Booklet Questions Hikohiko/Electricity in our homes 2015 Conductors Insulators Metals Electrons Cell Battery Bulb Switch Series Parallel Resistance Ohms Resistor Volts Watts Fuse Amps Ammeter Voltmeter Energy Power Power pack Key definitions to learn: Current Voltage (potential difference) Energy source Energy user Conductor Insulator Series circuit Parallel circuit Fuse This is the flow of charge around a circuit. It can only flow if the circuit is complete. This is a measure of the energy given to each charge as it flows through the circuit component. A source of energy to drive electrons through a circuit e.g a battery A circuit component e.g. a lamp or resistor A substance that conducts electricity e.g. copper wire, nichrome wire, graphite. Some conductors are better than others. A substance that is a poor conductor of electricity e.g. plastic, rubber, wood. The current flows from one component to the next , all components are on the same pathway. The current is the same at any point in a series circuit The current flows from the battery and splits up between two or more pathways. The sum of the current in the branches is equal to the total current flowing. Fuses are a safety device. A fuse contains a small piece of high resistance wire designed to melt and ‘break’ the circuit when there is an excess of current due to device or circuit malfunction. Key Learning Points: Know your symbols: Year 10 Science Revision Booklet Questions Electrical Circuits Electricity is the flow of electrons around a circuit. Circuits can be shown using diagrams. All circuits need an energy source (a cell) and an energy user (e.g. a lamp). Rules for circuit diagram drawing: Use a sharp pencil and a ruler. Lines at the corners should be drawn at approximately 900. Use the correct symbols and the circuit needs switch. The circuit must start and finish at a cell Note For current to flow through the circuit the switch must be complete. So the switch must be closed. A V Ammeters measure current and are connected “in series” with the energy converter. Ammeters measure current in Amps i.e 2.0A. Voltmeters measure voltage (potential difference) and are connected “in parallel” across an energy converter or energy producer. Voltmeters measure voltage in volts i.e. 6.0V. Year 10 Science Revision Booklet Questions Series and Parallel Circuits The wiring in series and parallel circuits is different: Series Circuit Parallel Circuit The following wiring diagram show that when wired in a series and one bulb breaks then the circuit (loop) is broken so there is no path for the current. The other bulb goes out. However when one bulb breaks there is still a complete circuit (loop) in a parallel circuit. This is shown below. Household electrical circuits use parallel circuits. A series circuit has only one path A parallel circuit has more than one path Current in a series circuit is the same Current in a parallel circuit is divided at all points in the circuit between the branches Voltage in a series circuit is divided Voltage in a parallel circuit equal in all between the energy converters and adds branches to the total input voltage up to the total input voltage Advantage Advantage: -Easy to wire, only one path to follow. -if one bulb goes out, the other bulbs remain on. Year 10 Science Revision Booklet Questions Disadvantage: -if one bulb goes out, all the bulbs go out. -voltage is divided between components (eg bulbs may be dim) -voltage is same in each part, bulbs are bright Disadvantage -can be complicated/difficult to wire Resistance Resistance is a measure of how difficult it is for current to flow through a component. The resistance of a circuit is measured in Ohms, e.g 10 Ω Fuses Fuses are a safety device. A fuse contains a small piece of high resistance wire designed to melt and break the circuit when there is an excess of current due to device or circuit malfunction. Remember it is high current that causes electrocution (not voltage). Website URL for extra revision: http://www.bbc.co.uk/schools/ks3bitesize/science/physics/electricity_intro.shtml Year 10 Science Revision Booklet Questions Revision Questions: 1. Draw symbols for: a lamp / voltmeter /ammeter / open switch / resistor / fuse / cell / battery / powerpack (powersupply) 2. Name 4 rules used when drawing a circuit diagram. ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… ……………………………………………………………………………………………… 3. Draw a circuit diagram for the following: A cell, a bulb and an ammeter to measure the current though the bulb A cell, a bulb and a voltmeter to measure the voltage across the bulb A series circuit with 2 bulbs, a cell and an ammeter and a switch A parallel circuit with 2 bulbs, a cell and 3 ammeters A parallel circuit with 2 bulbs, 2 voltmeters, cell and a switch Diagrams: 4. What happens in a series circuit if one bulb goes out? …………………………………………………………………………………………….. 5. What happens in a parallel circuit if one bulb goes out? ……………………………………………………………………………………………… 6. Is the current the same at all points in a series circuit? ……………………………………………………………………………………………… 7. Is the current the same at all points in a parallel circuit? Explain your answer. ……………………………………………………………………………………………… 8. Is the voltage across 2 identical bulbs in a series circuit the same? Year 10 Science Revision Booklet Questions ……………………………………………………………………………………………… 9. Is the voltage across 2 identical bulbs in a parallel circuit the same? ……………………………………………………………………………………………. 10. What unit do you measure voltage in? ……………………………………………………………………………………………… 11. What unit do you measure current in? ……………………………………………………………………………………………… 12. Calculate power using the equation: power = voltage x current for a lamp which has a current of 3 Amps through it and a voltage of 12 Volts across it. (Power is measured in Watts). ……………………………………………………………………………………………… ……………………………………………………………………………………………… …………………………………………………………………………………………….. Year 10 Science Revision Booklet Questions Draw a mindmap for this unit: Add to it, as you develop your learning. Electricity Well done you have completed another revision unit. Now reflect on how you can improve further: Which aspects of the unit do I need to revise more carefully? Which aspects of the unit do I need help with? How will I seek this help?