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 Electric Motor Key words and phrases: Electricity, Motor, Magnetism, DC, AC, Battery, Coil, Magnet, Wire, Commutator, Brief Introduction An ​
electric motor​
converts electrical energy into mechanical energy. In normal motoring mode, most electric motors operate through the interaction between an electric motor's magnetic field and winding currents to generate force within the motor. Found in applications as diverse as industrial fans, blowers and pumps, machine tools, household appliances, power tools, and disk drives, electric motors can be powered by direct current (DC) sources, such as from batteries, motor vehicles or rectifiers, or by alternating current (AC) sources, such as from the power grid, inverters or generators. Small motors may be found in electric watches. Electric motors are used to produce linear or rotary force (torque), and should be distinguished from devices such as magnetic solenoids and loudspeakers that convert electricity into motion but do not generate usable mechanical powers, which are respectively referred to as actuators and transducers. Curriculum links Stage Year Australian Curriculum NSW VIC Stage 4 Year 7 VCSSU104 PW3 VCSSU130 9.3.5​
(pdf) Unit 3, Area of study 1 (pdf) Year 8 ACSSU155 Year 9 ACSSU182 Year 10 Stage 6 Years 11/12 ACSPH110 Stage Year Australian Curriculum NSW VIC Stage 4 Year 7 Year 8 Energy appears in different forms, including movement (kinetic energy), heat and potential energy, and energy transformations and transfers cause change within systems. Energy appears in different forms including movement (kinetic energy), heat, light, chemical energy and potential energy; devices can change energy from one form to another. Year 9 Year 10 Years 11/12 A changing magnetic flux induces a potential difference; this process of electromagnetic induction is used in step­up and step­down transformers, DC and AC generators, and AC Stage 5 Stage 5 Stage 6 Energy appears in different forms including movement (kinetic energy), heat and potential energy, and causes change within systems. Electric circuits can be designed for diverse purposes using different components; the operation of circuits can be explained by the concepts of voltage and current Motors are used in industries and the home usually to convert electrical energy into more useful forms of energy. Investigate and analyse theoretically and practically the operation of simple DC motors consisting of one coil, containing a number of loops of wire, which is free to rotate about an axis in a induction motors. uniform magnetic field and including the use of a split ring commutator. Stage 4 Discussion In this activity students are encouraged to plan their own experiment and compare measurements that can be made using an electric motor Students may find there are many ways to conduct this experiment ­ it about opening the field so that they may come up with their own research question. During the course of the experiment, students may: ­
Design some ‘safe’ and ‘unsafe’ machines ­
Make measurements Science inquiry questions ­
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What variables can you change? What other observations can you make about the motor? Does the size of the coils, magnet, battery matter? What other questions could you ask with this investigation? How could you improve this investigation to get better results List some applications about how different measuring devices will behave. Make some observations and write them down. Try and explain your observations and how the observations are connected. Remember, a prediction in science is a testable hypothesis. You must make a statement about what you think will happen, that can be tested. Applications of electric motors Stage 5 Discussion Students in Stage 5 may begin to question what affects the investigation of the capability of the motor. Students will be asked to list variables that can be controlled or changed etc. The student should list the variables that are to do with the experiment, as well as the measurement of the data. Science inquiry questions Control variable Independent variable Dependant variable Variable Measurement ­
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Determine relationship between volts and coil Determine an equation for the relationship What other questions could you ask with this investigation? How could you improve this investigation to get better results Stage 6 Discussion
In this activity students move beyond the observation of electric motors to more complex analysis of how all these measurement devices work together in a real life example. Student in stage 6 will be asked to understand the application of physics in a phone. Science inquiry questions ­
Conduct a risk analysis filling out the following table. List three risks to do with this investigation, and in an industry where motors and generators would be important. What are the consequences of those risks and your mitigation techniques, or precautions from stopping those risks come about. Rank each risk in terms of likelihood and impact and make a judgement about whether the experiment is safe or not. Risk Consequence Precaution Classroom Industry ­
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What other questions could you ask with this investigation? How could you improve this investigation to get better results The experiment: Making your very own Electric Motor with nothing but: ●
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1m insulated (enamelled) copper wire of fine gauge; 2 paper clips (preferably large ones); 1 button magnet (careful – strong and brittle); 1 1.5V ‘battery’ (the correct term is a dry cell – AA in this case); 15cm insulation tape (colour optional – sticky tape will do); 1 lump of plasticine (colour optional – blu tack will do too)? Large quantity of patience and perseverance. On the day, you will be shown how to make the motor – once. You will need to watch carefully as: 1. The wire is wound into a coil (around a marker pen or something similar) and tied off with the 2 ends of the wire like the axle of a wheel so the coil can spin; 2. The arms of the coil are cleaned of the insulation (very important to get this bit right); 3. The paperclips are bent and taped to the dry cell; 4. The button magnet is placed onto the side of the cell and the ‘motor’ is stuck to the bench with a lump of plasticine. 5. The coil is suspended in the bent paperclips and ....... Teachers: 1. Identify any prior knowledge learners (in different Stages) may bring with them to this activity; 2. Compile a list of outcomes able to be addressed by this activity from the syllabus; 3. AND consider ways of extending the activity (especially in terms of how measurement may be incorporated). Students: considering the following: 1. How could we make the motor spin in reverse? 2. What would happen if we used a bigger battery; a bigger coil; thicker wire; a stronger magnet (faster rotation or more powerful or more efficient or......)? 3. Why is it so important to be so careful removing the insulation (enamel) from the arms of the coil?