GCSE Electronics June 2007 Paper Ans Key

Version 1.0: 0807 abc General Certificate of Secondary Education Electronics 3432 Tier F Foundation Mark Scheme 2007 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. 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Registered address: AQA, Devas Street, Manchester M15 6EX Dr Michael Cresswell Director GeneralElectronics -AQA GCSE Mark Scheme 2007 June series 3 1 (a) transformer􀀹 (1 mark) (b) fuse􀀹 circuit breaker (any type)􀀹 (2 marks) (c) (i) green/yellow􀀹 (ii) brown􀀹 (iii) blue􀀹 (3 marks) (d) Any two from; do not work alone/know first aid/know how to get help/carry out risk assessment (other answers possible) 􀀹􀀹 (2 marks) (e) shock􀀹 paralysis􀀹 burning􀀹 (any two points) (2 marks) (Total 10 marks) 2 􀀹 limits current/voltage to current/current to voltage􀀹 􀀹 current flows only one way􀀹 􀀹 input transducer/temperature to resistance􀀹 􀀹 stores charge/smoothes/blocks dc􀀹 􀀹 output transducer/current to sound􀀹 (10 marks) (Total 10 marks) Electronics -AQA GCSE Mark Scheme 2007 June series 4 3 (a) (i) light sensor􀀹 (ii) display􀀹 (iii) light sensor􀀹 (iv) latch􀀹 (4 marks) (b) (i) latch􀀹 (ii) light sensor􀀹 (iii) ADC􀀹 (iv) display􀀹 (4 marks) (c) (i) latch􀀹 (ii) display􀀹 (2 marks) (Total 10 marks) 4 (a) OR􀀹 AND􀀹 NAND􀀹 (3 marks) (b) A B C D Q 0 0 0 1 0 0 1 1 1 1 􀀹 􀀹 1 0 1 1 1􀀹 1 1 1 0 0􀀹 􀀹 􀀹 (6 marks) Electronics -AQA GCSE Mark Scheme 2007 June series 5 (c) (1 mark) (Total 10 marks) 5 (a) (three terminal) regulator IC 􀀹 (1 mark) (b) (5 marks) (c) (i) R = V ÷ I = 5 ÷ 0.25 = 20Ω􀀹􀀹 (ii) P = V × I = 5 × 0.25 = 1.25W􀀹􀀹 (4 marks) (Total 10 marks) + 9V -12V battery I O C output 􀀹 􀀹 􀀹 􀀹 􀀹 B A 􀀹Electronics -AQA GCSE Mark Scheme 2007 June series 6 6 (a) (5 marks) (b) (i) af amplifier􀀹 (ii) demodulator􀀹 (iii) tuned circuit􀀹 (3 marks) (c) varying amplitude􀀹 constant carrier frequency􀀹 (2 marks) (Total 10 marks) 7 (a)(i) and (ii) (3 marks) (b) data present on the D input􀀹 is transferred to the Q output􀀹 when the clock signal goes high􀀹 (3 marks) V time D Q CK __ Q data input􀀹 clock input􀀹 output 􀀹 (allow output 􀀹) or aerial 􀀹 tuned circuit 􀀹 demodulator 􀀹 af amp􀀹 loudspeaker …….􀀹 Electronics -AQA GCSE Mark Scheme 2007 June series 7 (c) (4 marks) (Total 10 marks) D Q CK __ Q D Q CK __ Q input􀀹 D Q D Q output􀀹 􀀹 􀀹 or CK from Q Electronics -AQA GCSE Mark Scheme 2007 June series 8 8 (a) start (5 marks) (b) decision box input box a loop -any line that returns to a point earlier in the flow chart􀀹 output box process box (5 marks) (c) (i) 23s􀀹 (ii) green on for 10s longer􀀹 (iii) 2􀀹 (iv) 6s􀀹 (v) 56s􀀹 (5 marks) turn on red 􀀹􀀹 􀀹 􀀹􀀹 delay 20s input traffic sensor signal is sensor activated? 􀀹􀀹􀀹􀀹Electronics -AQA GCSE Mark Scheme 2007 June series 9 (d) input state of button is button pressed? 10s delay pedestrian symbol green 15s delay (5 marks) (Total 20 marks) pedestrian symbol red N Y 􀀹 􀀹 􀀹 􀀹 Electronics -AQA GCSE Mark Scheme 2007 June series 10 9 (a) (8 marks) (b) the maximum output current from logic gate or timer is less than 450 mA (required by LED), or 12V o/p > 4V required􀀹 (1 mark) (c) (i) 8V􀀹 (ii) 450 mA􀀹 (iii) R = V ÷ I = 8 ÷ 0.45􀀹 = 17.77Ω􀀹 (iv) 18 Ω (allow 20 Ω) 􀀹 (5 marks) reset +Vs discharge threshold output trigger control ground voltage +Vs 0V 555 IC P to next stage􀀹 􀀹 􀀹 􀀹 􀀹 􀀹 􀀹 􀀹 Electronics -AQA GCSE Mark Scheme 2007 June series 11 (d) (6 marks) (e) (10 marks) (Total 30 marks) monostable 20s􀀹 monostable 3s􀀹 monostable 20s􀀹 monostable 3s􀀹 red driver amber driver green driver R A G 􀀹 􀀹 􀀹 􀀹 􀀹 􀀹 􀀹 􀀹 collector emitter base 􀀹 􀀹 􀀹 􀀹 􀀹