20048 AC Science Year 6 Physical sciences

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How does electricity flow? Content focus: A complete circuit is needed for electricity to flow Inquiry skills: Questioning and predicting Planning and conducting Processing and analysing data and information Communicating Background information • Electrons in the outer shell of each atom in a metal wire are not fixed to a specific atom. When a circuit is complete and the battery provides the force (voltage) for the electrons to flow, the electrons in the outer shells move from one atom to the next. They continue to travel in this way until there is a break in the circuit and the flow stops. • Household wiring can be arranged as series and parallel circuits. From the mains to the meter box, the circuit is in series. This is why when there is a power cut, there is no power to the house, and when an electrician is working in the house, he or she can tum off the mains switch and know for sure that there is no power. • Students may notice the difference in light intensity of the globes in each circuit. The flow of electricity is affected by the resistance within the circuit. All globes act as resistors. In a series circuit, there is twice as much resistance so each globe is half as bright as a single globe in series would be. In a parallel circuit, each globe has its own circuit branch and the resistance for each is the same as for a single globe in series so each globe glows equally brightl y. • Useful websites: - - Preparation • 1\vo A4 cards, one w i th 'positive ( +)' and the other with 'negative (-)' written clearly in the centre. Small balls, enough for one per student. • Teachers will need to collect the electrical components as listed on page 61. The lessons • The most important thing for students to understand is that electricity travels as a continuous flow of electrons. If there is a break anywhere in the circuit, the electrons (and hence electricity) will cease to flow. • The movement of electrons in a circuit can be demonstrated. Students stand in a circle, all facing the same direction. Nominate one student to be the battery. This student wears a large positive sign ( +) on his or her back and a large negative sign (-) on the front. Nominate one student to be the switch. When the 'switch' student stands in line with the others, the switch is closed and the current flows. When he or she steps out of line, the flow stops. Each student is an atom of the metal wire. Give each a ball which represents the electrons in the outer shell of each atom. When the switch is closed, each student passes his or her ball forward with the left hand, receives the ball from behind in the right hand and transfers it to the left hand before passing it on. On command, the switch steps out of line and all ball movement must stop. • If students have difficulty making the activity on page 61 work, they can consider how accurately they have assembled each circuit and the possibility that the batteries may have run down or the globes have blown. Answers Page60 1. (a) The current will not flow because there is a break in the circuit. (b) The current will flow because there are no breaks in the circuit. ( c) The current will not flow because there is a break in the circuit as the switch is open. 2. (a) electrons - negatively charged particles (b) current - the flow of electrons from one atom to another ( c) resistance - the force that acts against the flow of electrons ( d) load - something that uses electricity (e) voltage - the force that pushes electrons around a circuit 3. (a) False (b) True (c) True 4. (a) Electrons flow from the negative end of the battery, through a circuit to the positive end. (b) Answers should be similar to: the negatively charged electrons are pushed from the negative end of the battery, through a circuit and return to the positive end of the battery. Science as a Human Endeavour question Use and influence of science • • Students can complete the activity using their own general knowledge or by researching the information. Page61 1. Hypothesis/Results Switch 1 - This is a series circuit and the current has only one path along which to flow. When the switch is turned off, both bulbs go out because there is no longer any current flowing. Switch 2 - This switch is arranged in series so when it is switched off, neither globe will work because the current has stopped flowing. When it is turned on, the globes will only work if their switches are also turned on. Switches 3 and 4 - These are arranged in parallel with their globes. If they are turned on, the globes will work if switch 2 is also turned on. If it isn't, neither globe will work. If either switch is turned off the other will still work if switch 2 is turned on. 2. Switch 1 - series; Switch 2 - series; Switch 3 - parallel; Switch 4 - parallel 3. Answer should be similar to: electrical components arranged in series will only work if there are no breaks in the circuit. Arranged in parallel, the components can work independently of one another. ©R.I.C. Publications Low Resolution Images Display Copy AUSTRALIAN CURRICULUM SCIENCE (Year 6) PP.I · www bl . . ncpu 1cat1ons.com.au · R.I.C. Publications ®
How does electricity flow? - I Imagine riding a bicycle on a path around a lake. If there are no obstacles on the path, you can easily complete the circuit and end up back where you started. In the same way, if there are no breaks in an electrical circuit, a current will start at a battery and flow around the circuit until it is back at the battery. If when cycling an obstacle falls on the cycle path behind you, it won't stop you completing the circuit because you have already passed that point. However, if a break occurs anywhere in an electric circuit at any time, the electricity stops flowing. On the bicycle path, there may be a tunnel to ride through or a bridge crossing over a stream, but these won't stop your progress. In an electric circuit, there may be a light globe or a door bell that uses the electricity but, like the tunnel or the bridge, they do not stop the flow of electricity. Perhaps a train line crosses the cycle path. When a train is due, warning lights flash and a gate comes down across the path, blocking the way. Until the train has passed and the gate is lifted, you will not be able to continue. A switch in an electric circuit is like that gate. It stops and starts the flow of electricity. Electric current Everything is made up of atoms, each of which has a positively charged core (called a nucleus) and number of concentric shells surrounding it. These shells contain tiny negatively charged particles called electrons. In metals, electricity is the flow of electrons from the outer shell of one atom to the outer shell of another. This flow of electrons is called a current. The path of the current is called a circuit. +ve a- battery -ve ® light gloue --/' --- open switch e e closed switch +ve flow of electrons closed switch Electric circuit A simple circuit consists of a battery to provide power, wires to carry the current and a load that uses the electricity; for example, light globe. The wires are connected from the positive end to the negative end of the battery. In between, a light globe is attached. A switch can be added to create or break the circuit so the globe can be switched on and off. 1 +ve open switch ©R.I.C. Publications Low Resolution Images Display Copy Voltage To make the electricity flow, a force is needed to push the electrons around the circuit. This force, which is called the voltage, is provided by the battery. The electrons flow from the negative terminal of the battery, along a wire to the load, then along another wire to the positive end of the battery. Resistance As a current flows through a circuit, the wire exerts a force against the flow of electrons. This force is called resistance. It causes friction by slowing down the movement of electrons. A thin wire slows the electrons more than a thick wire and creates more resistance. This is the same for the longer wire. It takes energy for electrons to move against the resistance along a wire. R.I.C. Publications ® www.ricpublications.com.au m AUSTRALIAN CURRICULUM SCIENCE (Year 6)
Page 1 and 2: Your partner in education YEAR 6 Ph
Page 3 and 4: Foreword Australian Curriculum Scie
Page 5 and 6: . Teachers notes FOUR-PAGE FORMAT (
Page 7 and 8: (g JeaA) :l:JN:11:JS Wn1n:JIUHn:J f
Page 9: _____ l_n_v_e_s_tigation format Tit
Page 13 and 14: Connecting circuits Electrical circ
Page 15 and 16: What are electrical conductors and
Page 17 and 18: Conductor or insulator? All materia
Page 19 and 20: How do light globes work? - I There
Page 21 and 22: Electromagnetism unplugged! Electro
Page 23 and 24: How do wind and water generate elec
Page 25 and 26: Making the most of water power Hydr
Page 27 and 28: ©R.I.C. Publications Low Resolutio
Page 29 and 30: Solar-powered pathways Solar-powere
Page 31 and 32: Which energy sources for the future
Page 33: Sustainable energy sources on tap c

20048 AC Science Year 6 Physical sciences

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