Results Plus: Examiner Comments This answer not only includes attraction between positive and negative charge but also explains that the hair spreads out because the negative charges repel. This part of the answer is Level 2. The answer also includes transfer of electrons causing the charge and the diagram shows charge separation for the balloon near the wall. This takes the answer to Level 3 and 6 marks are awarded. Results Plus: Examiner Tip Accurate diagrams are very useful when concepts are difficult to explain in words. Q9. (a) (ii) This question was mainly based on the act of cleaning a trophy which comprises a metal cup on a plastic base. Results Plus: Examiner Comments Many demonstrated a clear link between the thing moving and the direction. Some were more vague and omitted the words 'the base of' from a response such as that shown. Others scored the second mark using the (loose) idea of friction. There were the usual incorrect references to positive electrons and proton movement. Results Plus: Examiner Tip Take every opportunity to reinforce the concept that it is the negative electrons which move, either in electrostatics or when there is a current in a wire. Only in electrolysis, really, do positive charges move. Refer to the structure of the atom to provide a reason for this. (See also comments for 3bi.) (a) (iii) Normally, 'suggest' questions are worth a single mark. This particular item was worth two marks. Results Plus: Examiner Comments This response was only worth 1 mark. It is insufficient to say either 'metals are conductors' or 'the cup is earthed'. Both of these ideas are necessary for the suggestion. Misconceptions were rife. For example: some candidates referred to 'the base is earthed' others contradicted themselves by writing 'as metals are conductors, the electrons are held tightly in place' a common lack of precision was that 'metals are not insulators', which is not the same as 'metals are conductors' metals can be charged provided they are insulated. Note this is different from saying they are insulators.
Results Plus: Examiner Comments This answer not only includes attraction between positive and negative charge but also explains that the hair spreads out because the negative charges repel. This part of the answer is Level 2. The answer also includes transfer of electrons causing the charge and the diagram shows charge separation for the balloon near the wall. This takes the answer to Level 3 and 6 marks are awarded. Results Plus: Examiner Tip Accurate diagrams are very useful when concepts are difficult to explain in words. Q9. (a) (ii) This question was mainly based on the act of cleaning a trophy which comprises a metal cup on a plastic base. Results Plus: Examiner Comments Many demonstrated a clear link between the thing moving and the direction. Some were more vague and omitted the words 'the base of' from a response such as that shown. Others scored the second mark using the (loose) idea of friction. There were the usual incorrect references to positive electrons and proton movement. Results Plus: Examiner Tip Take every opportunity to reinforce the concept that it is the negative electrons which move, either in electrostatics or when there is a current in a wire. Only in electrolysis, really, do positive charges move. Refer to the structure of the atom to provide a reason for this. (See also comments for 3bi.) (a) (iii) Normally, 'suggest' questions are worth a single mark. This particular item was worth two marks. Results Plus: Examiner Comments This response was only worth 1 mark. It is insufficient to say either 'metals are conductors' or 'the cup is earthed'. Both of these ideas are necessary for the suggestion. Misconceptions were rife. For example: some candidates referred to 'the base is earthed' others contradicted themselves by writing 'as metals are conductors, the electrons are held tightly in place' a common lack of precision was that 'metals are not insulators', which is not the same as 'metals are conductors' metals can be charged provided they are insulated. Note this is different from saying they are insulators.