Arre bhai, just remember this: draw your principal axis with a ruler, mark your focal points and centre clearly, and always show at least two rays meeting to form the image. The examiners want to see those construction lines, so never erase them. I know because I'm sketching them on my notebook's margin next to shampoo price calculations—if my lines can be clean after a long day at the salon, yours can be too in the exam.
#exams#study
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