2010 HSC Notes from the Marking Centre — Electrotechnology
This document has been produced for the teachers and candidates of the Stage 6 course in Electrotechnology. It contains comments on candidate responses to the 2010 Higher School Certificate examination, indicating the quality of the responses and highlighting their relative strengths and weaknesses.
This document should be read along with the relevant syllabus, the 2010 Higher School Certificate examination, the marking guidelines and other support documents which have been developed by the Board of Studies to assist in the teaching and learning of Electrotechnology.Teachers and candidates are reminded that if candidates are undertaking the 240-hour VET Industry Curriculum Framework in Electrotechnology and they want to undertake the HSC examination in Electrotechnology, they need to be entered separately for the examination through Schools Online (Administration) by the due date that is published in the Higher School Certificate Events Timetable.
Teachers and candidates should be aware that examiners may ask questions that address the syllabus outcomes in a manner that requires candidates to respond by integrating the knowledge, understanding and skills they developed through studying the course.
Candidates need to be aware that the mark allocated to the question and the answer space (where this is provided on the examination paper), are guides to the length of the required response. A longer response will not in itself lead to higher marks. Writing in excess of the space allocated may reduce the time available for answering other questions.
Candidates need to be familiar with the Board’s Glossary of Key Words which contains some terms commonly used in examination questions. However, candidates should also be aware that not all questions will start with or contain one of the key words from the glossary. Questions such as ‘how?’, ‘why?’ or ‘to what extent?’ may be asked, or verbs may be used which are not included in the glossary, such as ‘design’, ‘translate’ or ‘list’.
- Candidates were required to identify two features of sustainable power generation. The majority of candidates identified one feature, such as the ability to continually use the sustainable source into the future or that the method of power generation was renewable. Very few candidates were able to identify two features.
- Most candidates listed three methods of producing electricity sustainably, other than ‘photovoltaic’ which was specifically excluded from the question.
- Most candidates could explain the method that they had identified, though poorer responses neglected to mention the mechanical generation phase of wind power, hydro-electricity, wave generation.
- Most candidates clearly identified the series connection with the cells of the battery.
- This question was not as well answered, with many candidates referring to either voltage or current, and only the better responses referring to both as the question asked.
- Most candidates understood that one cell becoming open circuit would result in 0 Volts.
- Most candidates identified the parallel connection of cells.
- Again in this context many candidates did not respond to both the voltage and the current changes in this combination of cells.
- Most candidates gave correct answers in this part.
- This question was not well answered, with many candidates not clearly recalling the formula for power. Instead of multiplying current by voltage, many responses used V=IR. Those better responses who had the correct formula also managed to recognise that the current in the circuit was 5 milli amps or 5 x 10-3 amps. Students and teachers of Electrotechnology are reminded that a formula sheet is not provided in this subject for the Higher School Certificate examinations.
- This question was also poorly answered, with few candidates fully understanding the relationship between voltage, current and power. If the current doubles, the power will go up by a factor of four. Some candidates worked through the problem mathematically using V=IR and P=VI to correctly calculate the increase in power and current.
- Many candidates had difficulty with this elementary electrotechnology concept. There were few fully correct responses to this question, with many candidates over-complicating the calculation of resistance by trying to tackle the calculations in one formula. Better responses broke up each part of the circuit into R1 and R2 as parallel, totalling 7.2 Ω, then R4 and R5 in series, totalling 16Ω, then taking this 16Ω and having it in parallel with R3 to create 4.36Ω. The resulting total of the three separately calculated sections of the circuit then became a simple series exercise of 7.2Ω + 4.36Ω + 33 Ω = 44.56Ω. The few better responses to this question took this more logical approach.
- Very few responses indicated a clear understanding that if R2 and R3 were open circuit, or effectively removed from the circuit, that current would flow directly through R1 then to R4 and to R5. Creating a series circuit where the simple addition of resistances is done. R1 + R4 + R5 and then onto R6, or 12Ω + 10Ω + 6Ω +33Ω =61Ω. Better responses then went onto using this 61Ω in the correct V = IR formula to find the current asked for in the question.
- In this question, candidates were asked to describe what would happen when the two switches were closed. In an electrotechnology context it was expected that responses would be able to identify that both lights would glow brightly, as many did, but it was also expected that the flow of current be included in a description. In providing characteristics and features, better responses indicated that they understood no current would flow through resistor R1. Very few candidates received full marks for this question.
- Better responses to this question indicated a full understanding of the flow of current, through R1 to allow Lamp 2 to glow dimmer than Lamp 1. Many candidates correctly identified that Lamp 1 would remain on at full brightness but did not include the effect on Lamp 2. In poorer responses, it was clear that candidates did not understand that some current would flow through R1 to Lamp 2.
- The majority of candidates used V= IR incorrectly here to calculate a current in the circuit, demonstrating a lack of full understanding that when both switches close, current can flow directly, avoiding R1. The correct response of 0 V was provided by very few candidates.
- As with i, many candidates provided a voltage from the circuit given, 12V, not recognising that the question asked about the voltage across R1.
In this question, candidates were expected to provide a detailed explanation for the choice of process, tools, customer service and safe methods. Many candidates structured their response into a numbered series of events. Better responses included the essential customer service elements, prior to, during and at the completion of the task.
Some candidates responded as though the 15 amp socket needed to be relocated, when the question clearly stated that the socket did not need relocating.
In better responses, candidates recognised that at 17 kg, the hand dryer would require a 2-person lift or some mechanical support during removal and refitting.
Some, however, indicated that one person would hold the dryer while another marked the holes out on the wall. Given the weight involved, another approach is preferred.
Poorer responses lacked the detail required by the question. Poorer responses advocated unsafe practices and ignored the use of PPE.
The concept of risk assessment was clearly understood by the majority of candidates. Many used a danger matrix indicating the risk, its severity and suggested usage controls to overcome that risk.
Poorer responses were unaware of the processes that could be used to manufacture the bracket and could not then risk assess appropriately. They did not produce a risk assessment nor did they assess the risks involved but merely specified some processes and usage controls, eg the wearing of PPE.
Many responses showed that candidates did not understand the concept of a job diary entry. Though the question stipulated the identification of tools, processes and equipment, many candidates did not respond to all aspects.
Better responses clearly listed the tools and processes to be used, the equipment required and sequenced these correctly, identifying correct practices and using professional industry standard terminology. Many understood the tapping drill and tapping process using a lubricant so the tap did not stick and break. A variety of methods suggested to manufacture the bracket were acceptable.
Poorer responses either used unusual methods or equipment that could be considered unsafe, such as an angle grinder to cut out the slot.
Very poor responses had difficulty interpreting the drawing as an orthographic or did not read the 6 mm thickness, leading them to inappropriate tools and process, such as tinsnips.