GCSE Electronics June 2008 Paper Ans Key

Version 1.0: 0708 abc General Certificate of Secondary Education Electronics 3432 Tier F Foundation Mark Scheme 2008 examination – June series Mark schemes are prepared by the Principal Examiner and considered, together with the relevant questions, by a panel of subject teachers. This mark scheme includes any amendments made at the standardisation meeting attended by all examiners and is the scheme which was used by them in this examination. The standardisation meeting ensures that the mark scheme covers the candidates’ responses to questions and that every examiner understands and applies it in the same correct way. As preparation for the standardisation meeting each examiner analyses a number of candidates’ scripts: alternative answers not already covered by the mark scheme are discussed at the meeting and legislated for. If, after this meeting, examiners encounter unusual answers which have not been discussed at the meeting they are required to refer these to the Principal Examiner. It must be stressed that a mark scheme is a working document, in many cases further developed and expanded on the basis of candidates’ reactions to a particular paper. Assumptions about future mark schemes on the basis of one year’s document should be avoided; whilst the guiding principles of assessment remain constant, details will change, depending on the content of a particular examination paper. Further copies of this Mark Scheme are available to download from the AQA Website: www.aqa.org.uk Copyright © 2008 AQA and its licensors. All rights reserved. COPYRIGHT AQA retains the copyright on all its publications. 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Registered address: AQA, Devas Street, Manchester M15 6EX Dr Michael Cresswell Director GeneralElectronics -AQA GCSE Mark Scheme 2008 June series 3 1 (a) blue􀀹 green􀀹 and yellow􀀹 brown􀀹 (b) earth􀀹 live􀀹 neutral􀀹 (c) earth pin􀀹 fuse􀀹 cable grip􀀹 (any order) Total – 10 2 resistor symbol􀀹 passive􀀹 bipolar transistor symbol􀀹 active􀀹 diode symbol􀀹 passive􀀹 MOSFET symbol􀀹 active􀀹 capacitor symbol􀀹 passive􀀹 Total – 10 3 (a) (i) light sensor􀀹 (ii) lamp􀀹 (iii) comparator􀀹 (b) (i) comparator􀀹 (ii) light sensor􀀹 (iii) monostable􀀹 (c) comparator􀀹 monostable􀀹 MOSFET􀀹 lamp􀀹 time􀀹 OR light sensor􀀹 comparator􀀹 monostable􀀹 driver􀀹 (4 max, -1 per error) Total – 10 Electronics -AQA GCSE Mark Scheme 2008 June series 4 4 (a) (i) two inputs labelled A and B􀀹 OR gate symbol􀀹 output labelled Q􀀹 (ii) A B Q 0 0 0􀀹 0 1 1􀀹 1 0 1􀀹 1 1 1􀀹 (b) (i) AND gate􀀹 (ii) high􀀹 high􀀹 Total – 10 5 (a) (i) transistor, or MOSFET, or (three terminal) regulator IC􀀹 switching or regulating as appropriate to above􀀹 (ii) Collector􀀹 Base􀀹 Emitter􀀹, or Drain􀀹Gate􀀹 Source􀀹, or i/p􀀹 com􀀹 o/p􀀹 as appropriate to above􀀹 (b) (i) resistor􀀹 limits current􀀹 (ii) 22􀀹 (iii) 3W􀀹 (iv) 5%􀀹 Total – 10 6 (a) (i) af amplifier􀀹 (ii) demodulator􀀹 (iii) tuned circuit􀀹 (iv) loudspeaker􀀹 (v) aerial􀀹 (b) integrated circuit􀀹 Electronics -AQA GCSE Mark Scheme 2008 June series 5 (c) (i) increases􀀹 (ii) stays the same􀀹 (iii) increases􀀹 (iv) increases􀀹 Total – 10 7 (a) (b) (i) resistor􀀹 (ii) 3.8V􀀹 (iii) 380Ω􀀹 (iv) 390Ω􀀹 (v) 38mW􀀹 Total – 10 clock data Q Q 􀀹 􀀹 􀀹 􀀹 inverse of Q􀀹 Electronics -AQA GCSE Mark Scheme 2008 June series 6 8 (a) start (b) (i) decision box input box a loop is any line that returns to a point earlier in the flow chart􀀹 output box process box input light sensor 􀀹 􀀹 􀀹 􀀹 􀀹 delay 60s turn on lamp is it dark? 􀀹􀀹􀀹􀀹Electronics -AQA GCSE Mark Scheme 2008 June series 7 (b) (ii) & (iii) (c) light level is inputted, is dark detected? 􀀹 if yes, is IR detected? 􀀹 if yes turn on lamp􀀹 wait 60s before repeat􀀹 (d) (i) turn off lamp occurs after 60s delay, then switches on again􀀹 (ii) “turn off lamp” 􀀹 (iii) on diagram above Total – 20 start input light level is it dark? is IR present? turn lamp off Y input IR sensor turn lamp on delay 60 s N N Y 􀀹 􀀹 turn lamp off correct box􀀹 correct position􀀹 Electronics -AQA GCSE Mark Scheme 2008 June series 8 9 (a) (b) (i) & (iii) (ii) 4V􀀹 (iv) 100kΩ􀀹 (c) (i) light sensor IR module output 0 0 1􀀹 0 1 1􀀹 1 0 1􀀹 1 1 0􀀹 (ii) NAND􀀹 _ + +12V 0V 2kΩ 1kΩ output 􀀹 􀀹 􀀹 (for both) 􀀹 􀀹 light sensor comparator logic gate timer lamp IR module 􀀹 􀀹 􀀹 􀀹 􀀹 􀀹Electronics -AQA GCSE Mark Scheme 2008 June series 9 (d) (i) & (ii) 1 mark for each correct component in ring􀀹􀀹 (e) (i) relay􀀹 (ii) diode􀀹 Total – 30 Paper Total – 120 reset +Vs discharge threshold output trigger t l +Vs 0V 555 IC to lamp􀀹 􀀹 􀀹 􀀹 􀀹 􀀹 􀀹 from logic gate􀀹