Class Plan Separating soluble and insoluble solids from solutions

							Parallel Circuits Name of Teacher: Date: Time of Class: Class Level: Topic: Caoimhe Lawlor 4 November 2008 2 pm Junior Certificate Parallel Circuits

Aim: To introduce the parallel circuit Objectives: By the end of the class the students should be able to . . .  Set up a circuit containing two bulbs in parallel  Distinguish between this circuit and the series circuit from the last class  Comment on their observations regarding brightness, independence of bulbs etc.  List the advantages and uses of parallel circuits  Draw a simple parallel circuit containing two bulbs and a switch Previous Knowledge: Students will have studied the introduction to electricity and series circuits. Teacher will have taught and prepared this class before. Own Real life Experience: Christmas tree bulbs (old and new) Problems: Students may have difficulty setting up this circuit using the circuit diagram. Students may get confused with series circuit. Opening 2 sets of Christmas lights at the top of the class. Refer back to the characteristics of series circuit, get students to draw circuit on board and briefly recall the layout. Light the old set of Christmas bulbs and ask prediction as to what will happen using information from previous class if one bulb is unscrewed. Lights will go out. Produce 2nd identical lights. Dwell on the fact that they look the same externally we are not able to see the set up on the wires. Ask for prediction again – lights stay on – discuss that these must be different in some way – introduce parallel circuit. Body Teaching Episode 1 Introduction Ask student to draw series circuit on the board from previous class. Recall how electricity moves though the apparatus. Students, in groups of 4, can collect the required apparatus and set this up quite quickly. Implementation Draw series circuit again, adding the second bulb to make in parallel. Draw attention to the connections. Ask students to predict how the electricity will flow in this apparatus and discuss voltage and amps. Discuss similarities and differences in layout with series circuit. Allow each student to set up this equipment. Look at each groups set up to ensure it is correct. Keep series circuit on teacher’s desk to reference. Student Activity - Group work experiments

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Teacher Activity

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Class discussion, recalling information from previous class and applying this knowledge to this experiment. Facilitating discussion and experimental process

Questions 1. What is the main difference between the circuit today and in the last class? 2. Which apparatus is different? 3. If a 3V battery is used, what is the voltage running through the battery? 4. If a 3V battery is used, what is the voltage running through the bulb in the series circuit demo? Closure Ask students to draw the circuit diagram into their copies, reinforcing the differences and similarities in set up to the series diagram. Discuss why each circuit is called series or parallel etc. Use OHP to show series circuit and reveal added bulb  parallel circuit. Teaching Episode 2 Introduction Refer students back to series set up on teacher’s desk and compare the two bulbs. Reinforce every piece of apparatus is the same, same voltage battery etc, just the lay out is different. Write observations in copies. Implementation Ask students to recall definition of voltage. Discuss the voltage of the battery and therefore the bulb and each consequent bulb in the previous series circuit. Discuss what the voltage of the bulbs in parallel could be, referring to their brightness to make a prediction before using a voltmeter. Allow students to find the values of potential difference and current using their multimeters. Make predictions regarding adding and removing of bulbs and what that would do to brightness and therefore voltage. Allow students to verify their predictions. 1. What affected the brightness of batteries yesterday? 2. Is brightness related to amps or voltage? 3. If a 3V battery is used and the brightness is the same for both bulbs in parallel and the bulb in series, what is the voltage running through each bulb? 4. Why is this circuit called a parallel circuit? 5. What would happen if another bulb was added in parallel? 6. What would happen if bulb 2 or bulb 3 was removed?

Closure Refer back to Christmas lights and uses of parallel circuits. What are the advantages of parallel circuits? Closure Introduce next topic of using formulae and calculations to find the voltage, current and resistance in a given circuit.

Resources 7 multimeters 14 bulbs 7 3V batteries 7 Switches Reflection

6 Groups of 4 students Blackboard Chalk OHP Acetates Crocodile Clips Wire 2 sets of distinguishable Christmas lights