2023 CCEA GCSE Technology and Design 8900 模擬試題連答案詳解

1. Coping saw – E (cuts curved/intricate shapes in thin sheet material). 2. Pillar drill – C (bench-mounted machine for accurate vertical holes). 3. Forstner bit – F (bores a flat-bottomed hole, e.g. to recess a bolt head). 4. Claw hammer – H (drives and removes nails). 5. Engineer's square – G (checks a true 90° angle). 6. Sliding bevel – D (marks/checks angles other than 90°). 7. Centre punch – B (marks a point to prevent drill wander). 8. Wood chisel – A (removes waste wood by paring/chopping). 9. Bandfacer/linisher – I (powered abrasive belt for smoothing/shaping edges). Answer: 1-E, 2-C, 3-F, 4-H, 5-G, 6-D, 7-B, 8-A, 9-I.

1 mark for each correctly matched pair (9 pairs in total). [1] each: 1-E; 2-C; 3-F; 4-H; 5-G; 6-D; 7-B; 8-A; 9-I. Max 9 marks.

1. Mild steel – F (common ferrous metal, rusts, car panels/structural sections). 2. Aluminium – G (lightweight non-ferrous metal, corrosion-resistant, cans/aircraft). 3. Acrylic – H (rigid glass-like thermoplastic, signage). 4. MDF – D (low-cost manufactured board, no grain, flat-pack furniture). 5. Oak – A (dense hard hardwood, quality furniture). 6. Brass – C (copper-zinc non-ferrous alloy, fittings/instruments). 7. Epoxy resin – E (thermosetting plastic, adhesive/casting resin). 8. Stainless steel – B (ferrous alloy with chromium/nickel, corrosion-resistant, cutlery/sinks). 9. PVC – I (tough thermoplastic, pipes/window frames). Answer: 1-F, 2-G, 3-H, 4-D, 5-A, 6-C, 7-E, 8-B, 9-I.

1 mark for each correctly matched pair (9 pairs in total). [1] each: 1-F; 2-G; 3-H; 4-D; 5-A; 6-C; 7-E; 8-B; 9-I. Max 9 marks.

Pop riveting (C) is the correct answer: a pop rivet is set using a rivet gun that only requires access to one side of the joint (the rivet's mandrel is pulled and snapped off from the near side), it is a fast, cold process suited to a production line, and it applies no heat, so the painted finish is not at risk. Soft soldering (A) is incorrect because it requires heat from a soldering iron, which risks damaging the painted finish, and typically needs access to both sides to apply solder and heat effectively to the joint area. Wood adhesive/PVA (B) is incorrect because it is designed for porous wood surfaces, not non-porous sheet aluminium, and would not form a reliable structural bond on metal. A mortise and tenon joint (D) is incorrect because it is a wood-jointing technique relying on an interlocking wood tenon and mortise cavity, which cannot be formed in thin sheet aluminium. Answer: C, Pop riveting.

6 marks awarded for the correct answer, C (Pop riveting), which correctly satisfies all three stated constraints (one-side access, speed, no heat). No marks for any other option, each of which fails at least one of the stated constraints as explained in the solution.

A dowel joint (D) is the correct answer: cylindrical wooden dowels are glued into matching holes drilled in both the leg and the rail, greatly increasing the total glued surface area compared with a simple flat joint, and mechanically interlocking the two pieces so that a straight pulling force must shear or withdraw the dowels themselves, not just the glue line — this gives strong resistance to being pulled apart, and once assembled the dowels are completely hidden inside the joint. A butt joint (A) is incorrect because it relies only on a small, flat glued face at 90° with no mechanical interlock, making it the weakest of the four options against a pulling force. A mitre joint (B) is incorrect for the same reason (a flat 45° glued face with no interlock) and is primarily chosen for appearance (hiding end grain at a corner), not strength. A lap joint (C) is incorrect because, although it has more glued surface area than a butt joint, the overlap remains visible on the surface of the assembled piece rather than being hidden, and it does not resist a direct pulling-apart force as effectively as the mechanically interlocking dowels. Answer: D, Dowel joint.

6 marks awarded for the correct answer, D (Dowel joint), which correctly satisfies both stated requirements (maximum resistance to being pulled apart, and being fully hidden). No marks for any other option, each of which fails at least one of the stated requirements as explained in the solution.

A shuttle valve (B) is the correct answer: it has two air inputs and one output, and allows air from either input to pass through to the output (an OR function), while an internal shuttle mechanism blocks/seals whichever input is not currently supplying air, preventing that air from escaping back down the other (unactuated) valve's line — exactly what is required to combine the two 3/2 valves safely into a single feed for the SAC. A unidirectional flow regulator (A) is incorrect because its function is to control the speed of a cylinder's stroke by restricting flow in one direction, not to combine two separate signal lines. A 5/2 valve (C) is incorrect because it is a valve with five ports and two switching positions, typically used to directly control a double acting cylinder (DAC), not to combine two other valves' outputs. A reservoir (D) is incorrect because it is simply a storage tank for compressed air, with no logic or valve-combining function. Answer: B, Shuttle valve.

5 marks awarded for the correct answer, B (Shuttle valve), which is the only component providing the required OR function while preventing back-flow between the two input lines. No marks for any other option, each of which performs a different pneumatic function, as explained in the solution.

(a) For a simple gear train, the idler gear (B) does not affect the overall ratio, only the direction. Gear ratio (C:A) = teeth on driven gear ÷ teeth on driver gear \( = \dfrac{60}{20} = 3 \), i.e. 3:1. (b) Output speed = input speed ÷ gear ratio \( = \dfrac{300}{3} = 100 \) rpm. (c) Gear A meshing with idler gear B reverses the direction once (A clockwise → B anticlockwise); idler gear B meshing with gear C reverses the direction a second time (B anticlockwise → C clockwise). Two reversals cancel out, so gear C rotates clockwise, in the same direction as gear A. Answer: (a) 3:1; (b) 100 rpm; (c) clockwise, same direction as A, because the idler gear causes two direction reversals which cancel out.

(a) [1] correct teeth values identified (60 and 20); [1] correct method (teeth on C ÷ teeth on A); [1] correct ratio (3:1). (b) [1] correct formula (speed A ÷ gear ratio); [1] correct substitution; [1] correct answer with unit (100 rpm). (c) [1] correct direction (clockwise/same as A); [1] correct reasoning (idler gear causes two reversals, which cancel out). Max 8 marks; OFR applies throughout from part (a).

(a) For two resistors in parallel: \( \dfrac{1}{R_t} = \dfrac{1}{R_2} + \dfrac{1}{R_3} = \dfrac{1}{200} + \dfrac{1}{300} = \dfrac{3}{600} + \dfrac{2}{600} = \dfrac{5}{600} \), so \( R_t = \dfrac{600}{5} = 120\ \Omega \) (or using \( R_t = \dfrac{R_2 \times R_3}{R_2+R_3} = \dfrac{200 \times 300}{500} = 120\ \Omega \)). (b) Total resistance \( = R_1 + R_t = 100 + 120 = 220\ \Omega \). (c) Using \( V = I \times R \), rearranged \( I = \dfrac{V}{R} = \dfrac{6}{220} = 0.02727\ A = 27.3\ mA \) (3 s.f.). Answer: (a) 120 Ω; (b) 220 Ω; (c) 27.3 mA.

(a) [1] correct parallel formula used; [1] correct substitution; [1] correct answer (120 Ω). (b) [1] correct method (R1 + parallel combination); [1] correct answer (220 Ω). (c) [1] correct rearrangement of Ohm's law (I = V/R); [1] correct answer to 3 s.f. with correct unit (27.3 mA, or 0.0273 A). Max 8 marks; OFR applies throughout from part (a).

(a) The two inputs are the operator's push-button and the roller-trip mechanism triggered by the cheese block. The processing (control) is carried out by the two 3/2 valves together with the shuttle valve, which determine whether and when compressed air reaches the cylinder. The output is the SAC's outstroke, which drives the wire blade down through the cheese. [3: 1 each for correct inputs, process, output] (b) If both 3/2 valves were connected directly to the same air line feeding the SAC, air pressurised by one valve could pass backwards down the other (unactuated) valve's line to its exhaust port instead of reaching the cylinder, so the system might not work reliably from both inputs. A shuttle valve has a floating shuttle inside that seals off whichever input is not currently supplying air, so it allows air from either the push-button valve or the roller-trip valve to reach the SAC (an OR function) while preventing this back-flow/loss of pressure. [3] (c) 1. The cheese block presses the roller of the roller-trip-operated 3/2 valve. 2. This switches the 3/2 valve, connecting the pressure source to its output line. 3. The air signal passes through the shuttle valve (sealing off the push-button valve's line) to the SAC. 4. The SAC extends (outstrokes), driving the wire blade down through the cheese block. [4: 1 mark per correctly ordered step] (d) The spring return automatically pushes the valve's spool back to its normal, unactuated position as soon as the actuating force (finger pressure, or the cheese block's contact with the roller) is removed, without needing a separate signal to reset it. [2] Once the triggering input is removed, both 3/2 valves return to their normal position, so the supply of air to the SAC is cut off and the air in the cylinder is vented to exhaust; the cylinder's own internal spring then returns the piston (and blade) to its retracted (instroke) position. [1] Max 13 marks.

(a) [1] both inputs correctly identified (push-button and roller trip); [1] process correctly identified (3/2 valves and/or shuttle valve controlling air flow); [1] output correctly identified (SAC outstroke/blade cutting cheese). (b) [1] recognises risk of air escaping/loss of signal if valves connected directly; [1] correct description of shuttle valve's OR function (either input can reach the output); [1] correct explanation that the shuttle seals the unused input, preventing back-flow. (c) [1] each for: roller trip pressed; 3/2 valve switches, connecting supply; signal passes through shuttle valve to SAC; SAC outstrokes/blade cuts cheese, in this order. (d) [1] spring automatically resets valve to normal position when actuation is removed, no manual reset needed; [1] air to SAC is cut off/exhausted once triggering input is removed; [1] SAC's own spring returns the piston/blade to retracted position. Max 13 marks.

(a) The input is the LDR sensing the ambient light level. The process is the potential divider setting Vout and the NPN transistor switching on or off (via the relay) depending on Vout. The output is the motor driving the ventilation fan. [3] (b) In a potential divider, the voltage across a component is proportional to its resistance relative to the total resistance: \( V_{out} = V \times \dfrac{R_{LDR}}{R_{fixed} + R_{LDR}} \). As it gets dark, the LDR's resistance increases, so it takes a larger share of the 6 V supply and Vout rises. Because Vout only rises above the transistor's 0.6 V switch-on voltage once the LDR's resistance is high (i.e. in darkness), the transistor switches on in the dark and stays off in bright light (when the LDR's resistance, and therefore Vout, is low). [3] (c)(i) Bright light: \( V_{out} = 6 \times \dfrac{1000}{20000+1000} = 6 \times \dfrac{1}{21} = 0.29\ V \) (2 s.f.). This is below 0.6 V, so the transistor is OFF. [2] (ii) Darkness: \( V_{out} = 6 \times \dfrac{10000}{20000+10000} = 6 \times \dfrac{10}{30} = 2.0\ V \). This is above 0.6 V, so the transistor is ON. [2] (d) The transistor can only switch a small current directly, and the motor circuit uses a separate, higher-voltage (12 V) supply that may draw a current too large for the transistor to switch safely. A relay uses the small transistor current to energise an electromagnetic coil, which mechanically closes a separate set of contacts able to switch the higher-current/higher-voltage motor circuit; this also electrically isolates the sensitive low-voltage control circuit from the motor circuit, protecting it from damage (e.g. back-emf, handled by a protection diode across the relay coil). Answer: (a) LDR input, potential-divider/transistor process, motor output; (b) LDR at bottom means resistance and Vout rise together as it darkens, crossing 0.6 V only in the dark; (c)(i) 0.29 V, OFF (ii) 2.0 V, ON; (d) relay isolates and allows the low-power transistor to switch the higher-power motor circuit safely.

(a) [1] input correctly identified (LDR/light level); [1] process correctly identified (potential divider setting Vout, transistor switching); [1] output correctly identified (motor/fan, via relay). (b) [1] correct statement that LDR resistance rises in the dark; [1] correct explanation that Vout therefore rises (LDR at bottom of divider takes a larger share of the supply voltage); [1] correct link to the 0.6 V threshold explaining why this switches the transistor on only in darkness. (c) [1] correct method/substitution for bright-light Vout; [1] correct value (≈0.29 V) with correct OFF conclusion; [1] correct method/substitution for dark Vout; [1] correct value (2.0 V) with correct ON conclusion. (d) [1] recognises the motor circuit needs more current/a different (higher) voltage than the transistor can switch directly; [1] correct description of the relay's function (small current energises coil, which closes contacts for the higher-power circuit); [1] correct point about electrical isolation/protection of the control circuit. Max 13 marks; OFR applies throughout part (c).

1. START symbol — begins the program. 2. INPUT symbol — reads the current soil moisture level from the sensor. 3. DECISION symbol — tests 'Is moisture level < threshold?'. 4. YES branch: OUTPUT symbol — switches the pump ON; then a WAIT symbol — pauses for 10 seconds; then OUTPUT symbol — switches the pump OFF. 5. NO branch: no pump action is taken (the pump remains OFF). 6. Both the YES branch (after the pump is switched OFF) and the NO branch feed into a feedback loop that returns to step 2 (the INPUT symbol), so the moisture level is continuously rechecked. Because the system must run continuously, no STOP symbol is used — the flowchart loops indefinitely back to the INPUT step. Answer: START → INPUT (moisture level) → DECISION (moisture < threshold?) → [YES] OUTPUT (pump ON) → WAIT (10 s) → OUTPUT (pump OFF) → loop to INPUT; [NO] → loop directly to INPUT (pump stays off).

[1] START symbol correctly used as the first step. [1] INPUT symbol correctly used to read the moisture sensor. [1] DECISION symbol correctly used, testing the moisture level against the threshold. [1] YES branch correctly leads to OUTPUT (pump ON). [1] WAIT symbol correctly used for the 10-second delay, placed after pump ON. [1] OUTPUT symbol correctly used to switch the pump OFF after the wait. [1] NO branch correctly shown as bypassing the pump ON/WAIT/pump OFF steps (pump remains off). [1] Feedback loop correctly shown returning to the INPUT step (not to START) from both branches. [1]-[2] correct, unambiguous symbol names used consistently throughout (up to 2 marks). [1] logical, fully correct ordering of all steps. [1] no STOP symbol used/description makes clear the process repeats continuously, consistent with the system requirements. Max 12 marks.

A good response should describe, in a clear logical order, a complete and realistic sequence such as: (1) Using a steel rule, try square and scriber (or pencil, for acrylic), mark out the 150 mm × 100 mm rectangle onto the protective film that still covers the acrylic sheet, using a card or hardboard template to ensure accuracy and consistency across the batch. (2) Cut the plaque to size along the marked lines, for example using a bandfacer/linisher to true up the edges after an initial rough cut with a fine-toothed saw (or a guillotine, if available for the material thickness), keeping the protective film in place throughout to prevent scratching. (3) Mark the positions of the two fixing holes using a steel rule and scriber, and use a centre punch to mark the exact hole centres so the drill bit does not wander. (4) Securely clamp the plaque in a machine vice or a simple jig on the pillar drill table (to prevent the acrylic cracking or spinning), and drill the two fixing holes using an appropriately sized twist drill bit at a suitable speed for plastic, backing the work with scrap material to prevent breakout as the bit exits. (5) File the cut edges using a flat file to remove saw marks, then progressively smooth them using wet-and-dry abrasive paper of increasing grade. (6) Peel off the protective film. (7) Polish the smoothed edges to a clear, glass-like finish, for example using a pedestal polisher with a buffing mop and polishing compound (or by carefully flame polishing the edge with a small gas torch, if appropriate equipment and training are available). (8) Engrave the memorial text/design onto the face of the plaque, for example using a laser engraver (fast, precise, and repeatable for a batch) or by hand engraving with an engraving tool and jig. (9) Carry out a final visual and dimensional quality check against the original specification (size, hole positions, edge finish, engraving legibility) before packaging. Throughout, safety precautions should include: wearing eye protection at all cutting, drilling, filing and polishing stages, as acrylic can produce sharp swarf/dust and polishing mops can catch and throw material; using and checking machine guards on the pillar drill, bandfacer and polisher before use; securely clamping/jigging the workpiece at every machining stage rather than holding it by hand, since acrylic can crack or grip and spin unexpectedly; tying back loose hair/clothing and removing jewellery near rotating machinery; and, if flame polishing, working in a well-ventilated area away from flammable materials and being aware acrylic fumes can be irritant. A response awarded Very Good marks will present a complete, realistic, correctly ordered sequence naming specific appropriate tools/equipment at each stage, explain briefly why each stage is carried out in that order (e.g. drilling before polishing to avoid damaging the polished edge, film kept on until after cutting/filing to protect the surface), and integrate specific, relevant safety precautions throughout rather than as an afterthought, using accurate technical vocabulary and clear, well-structured, fluent writing.

Level of Response marking. Limited [1]-[4]: a short or disorganised description with some correct tools/stages named but with significant gaps, incorrect ordering, or very limited/generic safety comments; weak use of specialist vocabulary. Satisfactory [5]-[8]: most stages of a sensible process are described in a broadly logical order (marking out, cutting, drilling holes, finishing edges, polishing, engraving), naming appropriate tools for most stages, with at least some relevant safety points included; some gaps or minor ordering issues may remain and specialist vocabulary is used reasonably well. Very Good [9]-[11]: a complete, realistic, correctly ordered manufacturing sequence from marked-out sheet to finished plaque, naming specific appropriate tools/equipment at every stage (marking out, cutting, hole drilling, edge finishing/polishing, engraving, quality check), with specific safety precautions integrated throughout (not just listed generically), clear reasoning for the order of operations, accurate technical vocabulary, and fluent, well-structured written communication.