Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
History of electric power transmission wikipedia , lookup
Electrical ballast wikipedia , lookup
Switched-mode power supply wikipedia , lookup
Voltage optimisation wikipedia , lookup
Resistive opto-isolator wikipedia , lookup
Stray voltage wikipedia , lookup
Current source wikipedia , lookup
Buck converter wikipedia , lookup
Surge protector wikipedia , lookup
Mains electricity wikipedia , lookup
P2: Physics for your future Page 1 of 4 Lesson P2.4 Current and voltage Specification learning outcomes 2.1 Describe how an ammeter is placed in series with a component to measure the current, in amps, in the component 2.2 Explain how current is conserved at a junction 2.3 Explain how the current in a circuit depends on the potential difference of the source 2.4 Describe how a voltmeter is placed in parallel with a component to measure the potential difference (voltage), in volts, across it [H] 2.5 Demonstrate an understanding that potential difference (voltage) is the energy transferred per unit charge passed and hence that the volt is a joule per coulomb HSW statements Prior learning from KS 3 HSW 3 many phenomena can be explained by developing and using scientific theories, models and ideas Year 8 Explain, using data and a simple model, the differences between series and parallel circuits HSW 11 presenting information, developing an argument and drawing a conclusion, and using scientific, technical and mathematical language, conventions and symbols and ICT tools Year 9 Investigate current and voltage in circuits and draw conclusions from a range of data Exemplar teaching activities Starter: Yo! Sushi Explain to students how the Yo! Sushi restaurants work (a conveyor belt winds through the restaurant and diners take dishes from it as they pass, then pay at the end depending on how many and which kinds of dishes they have eaten). Ask students to compare how the restaurants work to an electric circuit, listing similarities and differences. Main: Conservation of current demonstration Demonstrate that current is conserved at a junction using demonstration ammeters. This could also be done as a class practical if time and resources allow. See the Teacher and technician practical sheet P2.4 (2) for full details. Plenary: Spot the mistakes Ask students to work in small groups to draw three circuit diagrams, each of which contains at least one mistake. These can include things such as the readings on different ammeters in a circuit or a voltmeter placed in a circuit to measure the potential difference. Groups swap drawings and try to identify the mistakes. Check selected samples to make sure that there are no misconceptions being reinforced. Homework: Worksheets P2.4c (for students requiring extra support) and P2.4d (for those working at a higher level) contain questions on Current and circuits. Main differentiation Resource sheets Stretch: Ask students to predict what will happen to the current readings if a third bulb is added to the same branch. Teacher and technician practical sheet P2.4 (2) Support: Students could act out a circuit, with each student being a unit of charge. All go through a 'cell', but then split up to follow two separate paths. They should be able to see that the number going through the 'cell' must be the same as the total going through the two branches. Worksheet P2.4c Worksheet P2.4d BTEC Links P2: Physics for your future Page 2 of 4 Lesson P2.5 Investigating voltage, current and resistance (Practical) Specification learning outcomes 2.6 Investigate the relationship between potential difference (voltage), current and resistance HSW statements HSW 1 the collection and analysis of scientific data HSW 2 the interpretation of data, using creative thought, to provide evidence for testing ideas and developing theories HSW 3 many phenomena can be explained by developing and using scientific theories, models and ideas HSW 5 planning to test a scientific idea, answer a scientific question or solve a scientific problem HSW 6 collecting data from primary or secondary sources, including the use of ICT sources and tools HSW 7 working accurately and safely, individually and with others, when collecting first-hand data HSW 8 evaluating methods of data collection and considering their validity and reliability as evidence HSW 10 using both qualitative and quantitative approaches HSW 11 presenting information, developing an argument and drawing a conclusion, and using scientific, technical and mathematical language, conventions and symbols and ICT tools Prior learning from KS 3 N/A Exemplar teaching activities Starter: Blowing bulbs Use a low voltage bulb in a circuit where the voltage produces too high a current for it, and show students that the bulb 'blows'. Set up the circuit again with a new bulb, but this time with a resistor in the circuit as well. Show students that the bulb survives this time, and ask them to suggest why this is. Main: Students follow the instructions on Worksheet P2.5b. This prompts students to take current and voltage readings at several different power pack voltage settings for each of 5 resistors. The range of data that students need to collect is given on Worksheet P2.5c which students will also need. This sheet guides students through recording, considering their results, and evaluating their investigation. You could ask students to come up with one or two further hypotheses, based on their observations in this practical. Main differentiation N/A Resource sheets Teacher and technician practical sheet Worksheet P2.5b Worksheet P2.5c BTEC Links P2: Physics for your future Page 3 of 4 Lesson P2.6 Changing resistances Specification learning outcomes 2.7 Explain how changing the resistance in a circuit changes the current and how this can be achieved using a variable resistor 2.8 Use the equation: potential difference (volt, V) = current (ampere, A) resistance (ohm, Ω), V = I R 2.9 Demonstrate an understanding of how current varies with potential difference for the following devices: a) filament lamps b) diodes c) fixed resistors 2.10 Demonstrate an understanding of how the resistance of a light-dependent resistor (LDR) changes with light intensity 2.11 Demonstrate an understanding of how the resistance of a thermistor changes with change of temperature (negative temperature coefficient thermistors only) HSW statements HSW 3 many phenomena can be explained by developing and using scientific theories, models and ideas HSW 11 presenting information, developing an argument and drawing a conclusion, and using scientific, technical and mathematical language, conventions and symbols and ICT tools HSW 10 using both qualitative and quantitative approaches Prior learning from KS 3 Year 9 Investigate current and voltage in circuits and draw conclusions from a range of data Exemplar teaching activities Starter: Design a circuit Ask students to design an automatic control circuit for car lights that go on when it gets dark or a thermistor that changes with temperature (or any other simple task they may come up with themselves). Keep students' ideas and revisit later in the lesson so they can amend their ideas if necessary. Main: Varying the potential difference practical Students obtain data and draw current–voltage graphs for fixed resistors, filament lamps and diodes. Students need not test fixed resistors if they have done the practical work in lesson P2.5. See Worksheet P2.6a and the Teacher and technician practical sheet P2.6 (2) for full details. Plenary: Components and graphs Worksheet P2.6c provides a set of cards showing the different components looked at in this lesson, their circuit symbols and graphs showing their characteristics. Ask students to match up the cards and label the axes on the graphs. Homework: Worksheet P2.6e is designed for students working at a higher level and provides questions about the components studied in this lesson. Students will also need a sheet of graph paper. Main differentiation Resource sheets Stretch: Do not give students the part of the worksheet showing them how to tabulate and present their results, so they can work out for themselves the best way of displaying the data. Worksheet P2.6a Support: Help students to draw a table for their results and help them to work out the resistances for each set of current and voltage readings. They may also need help plotting the negative currents and voltages on a graph. Worksheet P2.6e Teacher and technician practical sheet P2.6 (2) Worksheet P2.6c BTEC Links P2: Physics for your future Page 4 of 4 Lesson P2.7 Transferring energy Specification learning outcomes 2.12 Explain why, when there is an electric current in a resistor, there is an energy transfer that heats the resistor [H] 2.13 Explain the energy transfer (in 2.12 above) as the result of collisions between electrons and the ions in the lattice 2.14 Distinguish between the advantages and disadvantages of the heating effect of an electric current 2.15 Use the equation: electrical power (watt, W) = current (ampere, A) potential difference (volt, V), P = I V 2.16 Use the equation: energy transferred (joule, J) = current (ampere, A) potential difference (volt, V) time (second, s), E = I Vt HSW statements Prior learning from KS 3 Exemplar teaching activities HSW 3 many phenomena can be explained by developing and using scientific theories, models and ideas Year 7 Use a model to describe the flow of current and begin to recognise some of its strengths and weaknesses Starter: Heating wire wool demonstration HSW 11 presenting information, developing an argument and drawing a conclusion, and using scientific, technical and mathematical language, conventions and symbols and ICT tools Year 8 Explore different models to explain the flow of current and the transfer of energy Students have already met the equation for calculating power from current and potential difference, in P1 Topic 5. Lesson P1.29 included a practical to measure the power of various low voltage devices. This could be repeated here. Year 9 Evaluate different models used to explain the flow of current and the transfer of energy Write some typical power ratings on the board (e.g. electric drill 1500 W) and ask students to work in pairs to create three power or energy calculation questions each using this data. They should also write mark schemes for their answers. They then swap questions with their partners and work out the answers. Higher tier students should be encouraged to include questions that involve changing the subject of the equation. HSW 10 using both qualitative and quantitative approaches HSW 12 the use of contemporary science and technological developments and their benefits, drawbacks and risks Demonstrate the heating effect of a current using wire wool. See the Teacher and technician practical sheet P2.7 for full details. Main: Calculating power Plenary: Power questions Homework: Worksheets P2.7b (for students requiring extra support) and P2.7c (for those working at a higher level) contain questions on Heating and power. Main differentiation Resource sheets Stretch: Ask students to explain why the heating effect of a current increases with a higher current. Teacher and technician practical sheet P2.7 Support: Work through the examples step by step on the board, asking students to tell you where various numbers should go. Worksheet P2.7b Worksheet P2.7c BTEC Links