WELSH JOINT EDUCATION COMMITTEE
CYD-BWYLLGOR ADDYSG CYMRU
General Certificate of Secondary Education Tystysgrif Gyffredinol Addysg Uwchradd
MARKING SCHEMES
SUMMER 2004
ELECTRONICS (MODULAR)
INTRODUCTION
The marking schemes which follow were the ones used by the WJEC for the SUMMER 2004 examination in the GCSE ELECTRONICS papers . They were finalised after detailed discussion at examiners' conferences by all the examiners involved in the assessments. The conferences were held shortly after the papers were taken so that reference could be made to the full range of candidates' responses, with photocopied scripts forming the basis of discussion. The aim of the conference was to ensure that the marking schemes were interpreted and applied in the same way by all examiners.
It is hoped that this information will be of assistance to centres but it is recognised at the same time that, without the benefit of participation in the examiners' conference, teachers may have different views on certain matters of detail or interpretation.
The WJEC regrets that it cannot enter into any discussion or correspondence about these marking schemes.
Electronics – May 2004 E1 – Marking Scheme
Foundation Tier
1. (a) Capacitor 1
(b) LDR 1
(c) LED 1
Total 3
2. (a) AND 1
(b) push switch 1
(c) transducer driver 1
Total 3
3. Each correct sequence (1) ´ 2 [μVàmV; mVàV] 2
Total 2
4. (a) tilt (1)
(b) reed (1) 2
Total 2
5. A 1
Total 1
6. (a) 6 (1)
(b) 14 (1)
(c) 20 (1)
(d) 10 (1) 4
Total 4
7. (a) (i) 4 [V] 1
(ii) 20 m[A] or 0ּ02 [A] 1
(b) correct use of 4 V and 20 mA [e.c.f.] (1)
3
(c) 220 [Ω] or 180 [Ω] 1
Total 6
8. (a) temperature sensing (1)
(b) OR(1)
(c) Transistor switch / transducer driver (1)
Total 3
9. (a) Base labelled. 1
(b) (i) 0ּ4 [V] (1)
(ii) 6 [V] (1) 2
(c) (i) 0ּ7 [±0ּ1] [V] (1)
(ii) 0 [V] [accept 0 – 0ּ2] (1) 2
(d)
3
Total 8
10. (a) (i) 30 k[Ω] 1
(ii) 2
(b) 10 (1)
0 (1) [accept ‘OFF’] 2
(d) correct symbols for [variable] resistor (1) & thermistor (1) thermistor [accept LDR] in upper position (1) 3
Total 8
Higher Tier
1. (a) temperature sensing (1)
(b) OR(1)
(d) Transistor switch / transducer driver (1)
Total 3
2. (a) (i) 4 [V] 1
(ii) 20 m[A] or 0ּ02 [A] 1
(b) correct use of 4 V and 20 mA [e.c.f.] (1)
3
(c) 220 [Ω] 1
Total 6
3. (a) 200 mA (1)
(b) 20k (1)
(c) 20 (1)
(d) 2000k (1) 4
Total 4
4. (a) 6 (1)
(b) 14 (1)
(c) 20 (1) [no e.c.f.]
(d) 10 (1)
Total 4
5. (a) 30 k[Ω] 1
(b) 2
(c) 10 (1)
0 (1) 2
(d) correct symbols for [variable] resistor (1) & thermistor (1) thermistor [accept LDR] in upper position (1) 3
Total 8
6. (a) 3
(b) 2
(c) (i) 0ּ7 [±0ּ1] [V] 1
(ii) 2ּ4 [V] e.c.f. 1
(d) 2
Total 9
7. (a) carries on flashing [or equiv.] (1)
(b) no flashing – on in the light (1)
(c) no flashing – stays on once triggered. (1) 3
Total 3
8. (a) 6 (1) k[Ω](1) 2
(b) 4 [V] 1
Total 3
E2 June 2004 - Marking Scheme for the Foundation Paper
1. (a) position sensor 1
(b) counter 1
(c) buzzer 1
Total Mark 3
2. (a) temperature sensor 1
(b) to change analogue signal [from temperature sensor] to digital 1
Total Mark 2
3. (a) 4 1
(b) 4 1
(c) 4 1
(d) NAND 1
Total Mark 4
4. (a) 2 (1); 1 (1) 2
(b) 5 [V] 1
(c) Any suitable application; e.g. clock 1
Total Mark 4
5.
3
Total Mark 3
6. (a) (i) 1
(ii) 1
(b) (i)
3
(ii) NAND [or e.c.f. from (b)(i)] 1
Total Mark 6
7. Q output [change to] 0 at time 2 1
Q output change to 1 at time 6 1
Q output changes to 0 at time 10 1
Q amplitude = 1 1
Total Mark 4
8. (a) 9 (1); 10th (1) e.c.f. 2
(b) Connection from C to Reset [penalise extra connections] 1
Total Mark 3
9. (a) (i) buzzer [comes on] (1)
(ii) buzzer [stays on] (1) 2
(b) to reset the circuit [or equiv.] 1
(c) any suitable application e.g. burglar alarm for house/car
security system 1
Total Mark 4
8. (a) (i) AND (1) (ii) NOT A [or ](1)
(iii) NOT (A or B) [or equiv.](1) 3
(b) 3 correct gates to correct outputs (2)
[1/2 correct gates to correct outputs (1)]
correct inputs (1) 3
(c) Easy to change system [without complete rewiring] 1
[or answers referring to fewer chips/less space/lower layout complexity]
Total Mark 7
E2 June - Marking Scheme for the Higher Paper
1. (a) 4 (1)
(b) 4 (1)
(c) NAND (1) 3
Total Mark 3
2. (a) 2 (1); 1 (1) 2
(b) 5 [V](1) ; 4 [s] (1) 2
Total Mark 4
3.
3
Total Mark 3
4. Q output [change to] 0 at time 2 1
Q output change to 1 at time 6 1
Q output changes to 0 at time 10 1
– 1 for falling-edge triggered; – 1 for poor amplitude
Total Mark 3
5. Connections: C to AND i/p (1)
A to AND i/p (1); AND o/p to Reset (1)
– 1 for each additional connection 3
Total Mark 3
6. (a) Buzzer [accept: thyristor] comes on and stays on. 1
(b) to reset circuit [or equiv.] 1
(c) any suitable application e.g. burglar alarm for house/car
security system 1
Total Mark 3
7. (a) (i) AND (1) (ii) NOT A [or ](1)
(iii) NOT (A or B) [or equiv.](1) 3
(b) 3 correct gates to correct outputs (2)
[1/2 correct gates to correct outputs (1)]
correct inputs (1) 3
(c) Easy to change system [without complete rewiring] 1
Total Mark 7
8. (a)
3
(b) NAND equivalent of AND (1)
NAND equivalent of NOT (1)
NAND equivalent of OR (1) 3
(c) correct pair crossed out 1
[extra crossings out penalised]
Total Mark 7
9. (a) MOSFET/Darlington/transistor/relay/transducer driver
to boost / amplify current (or power) capability. 1
(b) 1ּ1 ´ 10 ´ 1ּ8 (1) = 19ּ8 s (1) [e.c.f. on indices] 2
(c) Correct shape (1)
Rising output at t = 1ּ7 (1)
Falling output at t = 4ּ3 (1)
No output change at t = 6ּ2 (1) 4
Total Mark 7
GCSE Electronics – June 2004 Terminal Paper – Marking Scheme
Foundation Tier
1. (a) LDR 1
(b) LED 1
(c) Correct symbol 1
Total 3
2. (a) (i) C 1
(ii) A 1
(iii) 36 [kΩ] 1
(b) Band 1: Brown (1)
Band 2: Grey (1)
Band 3: Orange (1) 3
(c) (1) 2
Total 8
3.
3
Total 3
4. (a) (i) NOT [or inverter] (1)
(ii) AND (1)
(iii) OR (1) 3
(b)
3
Total 6
5. (a) Each correct sequence (1) ´ 3 3
(b) Thermistor [accept phonetic spelling!] 1
(c) Correct symbol [b.o.d.] 1
Total 5
6. (a) 1½ minutes 1
(b) Y 1
(c) (i) 1010 1
(ii) DàAND (1); BàAND (1); ANDàReset (1) [e.c.f.] 3
(d) (i) 16 1
(ii) 8 [e.c.f. = ½ (d)(i)] 1
(e) Advantage (1); description (1) 2
Total 10
7. (a) (i) Name of source e.g. microphone 1
(ii) amplify [or boost] voltage/signal 1
(iii) amplify current [allow: power] 1
(b) (i) A 1
(ii) A 1
Total 11
8. (a) [ignore any unit given] 2
(b) (i) Use of 50 mV (1). Answer = 500 mV (1) 2
(ii) period (1); phase (1); 500 [±20] mV peak(1) 3
(c) Frequency range (1) where gain does not drop (1)[or equiv.] 2
Total 9
9. (a) ariel (1); tuned circuit (1); demodulator (1); loudspeaker (1) 4
(b) Approx. correct no. of peaks [allow 3 – 5] (1)
Approx correct amplitude [up to 2 cm] (1)
[N.B. Extra line underneath (–1)] 2
Total 6
10. (a) e.g. light or pressure sensor 1
(b) increments by one [adds one] 1
(c) ‘Has person entered?’ [or equiv.] in top decision box (1)
Loop back to either side of ‘Set counter’ (1)
Yes/No on decision box (1)
‘Counter +1’ [or equiv] in middle box (1)
Loop back to below ‘set counter’ box (1)
Sound alarm (1) 6
Total 8
11. (a) 4 correct readings [out of 0ּ4, 1ּ0, 0ּ8, 0ּ2, 0ּ8] (4 ´ 1) 4
[Original signal copied à 0; digital joined = 2 max]
(b) (i) 0101 (1)
1000 (1) 2
(ii) 3 V 1
Total 7
Higher Tier
1. (a) Each correct sequence (1) ´ 5 5
(b) AND 1
(c) correct symbol 1
Total 7
2. (a)
3
(b) 2
Total 5
3. (a) 1 [V] 1
(b) 2
(c) Use of 2
Total 5
4. (a) (i) Q = 1
(ii) P = (1); R = (1) 2
(b) Correct NOT connection (1); Correct AND connections (1) 2
(c) Correct AND equivalent (1)
Correct NOT equivalent (1)
Correct OR equivalent (1) 3
Total 8
5. (a) 1½ minutes 1
(b) Y 1
(c) (i) 1010 1
(ii) DàAND (1); BàAND (1); ANDàReset (1) [e.c.f.] 3
(d) (i) 16 1
(ii) 8 [e.c.f. = ½ (d)(i)] 1
(e) Advantage (1); description (1) 2
Total 10
6. (a) (i) Name of source e.g. microphone 1
(ii) amplify [or boost] voltage/signal 1
(iii) amplify current [allow: power] 1
(b) (i) A 1
(ii) A 1
(c) (i) Correct points[ignore 0 – 2 kHz] (2); correct curve (1) 3
(ii) gain of 35 marked (1); upper limit marked (1) 2
(iii) point read ± 1 square. 1
Total 11
7. (a) [ignore any unit given] 2
(b) (i) Use of 50 mV (1). Answer = 500 mV (1) 2
(ii) period (1); phase (1); 500 [±20] mV peak(1) 3
(c) Use of (1). Answer = 1ּ3 V (1) [allow ‘up to 1ּ29 V’] 2
Total 9
8. (a) Positive signal only (1); with r.f. (1) 2
(b) ~ correct frequency (1); ~correct amplitude (1) 2
Total 4
9. (a) 4 correct readings [out of 0ּ4, 1ּ0, 0ּ8, 0ּ2, 0ּ8] (4 ´ 1) 4
[Original signal copied à 0; digital joined = 2 max]
(b) (i) 1000 1
(ii) 3 V 1
Total 6
10. ‘Has person entered?’ [or equiv.] in top decision box (1)
Loop back with ‘No’ to either side of ‘Set counter’ + ‘Yes’(1)
‘Counter +1’ [or equiv] in middle box (1)
‘Is counter 10?’ [or equiv.] in lower decision box.(1)
Loop back with No/Yes to below ‘set counter’ box (1) 5
Total 5
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