2023 Oct/Nov · Paper 12 · Q2 (a(i), a(ii), b, c(i), c(ii), c(iii))6 marksSensors, actuators and ADC/DAC
2023 May/June · Paper 12 · Q34 marksInput devices
2023 May/June · Paper 12 · Q9 (a, b)8 marksDirect data entry devices (bar codes, RFID, QR)
2023 May/June · Paper 12 · Q13 (b, c)4 marksOutput devices · Sensors, actuators and ADC/DAC
2022
2022 Oct/Nov · Paper 12 · Q11 (b)3 marksSensors, actuators and ADC/DAC
2022 May/June · Paper 12 · Q12 marksInput devices
2022 May/June · Paper 12 · Q22 marksOutput devices
2022 May/June · Paper 12 · Q54 marksDirect data entry devices (bar codes, RFID, QR)
No questions match this filter.
References only, not question text. Open Official paper ↗ where Cambridge publishes the paper,
or see the official Cambridge past-papers page; for other papers, ask your
school. “Paper 42” means Paper 4, variant 2.
Practice questions
Original questions written by HomiLabs in the style of the exam, with answers and mark schemes. They are not
Cambridge past paper questions and have not been reviewed by Cambridge. Try each one before opening the answer.
Q1Direct data entry devices (bar codes, RFID, QR) · Core · Paper 1 style · 3 marks
(a)A public library in Lahore is replacing the bar code labels in its books with RFID tags. State two advantages to the library of using RFID tags rather than bar codes.[2]
(b)State one disadvantage to the library of using RFID tags.[1]
Show answer
(a) Any two, e.g. several books can be read at the same time; no line of sight is needed so books need not be turned to face the reader; tags can be read through covers/bags; tags are harder to damage than printed labels; data on the tag can be changed/updated.
1 mark each for any two distinct advantages. Do not accept 'faster' alone without a reason.
(b) Any one, e.g. tags cost more than bar code labels; tags can be read by unauthorised readers nearby; signals can be blocked/jammed by metal or interference; tags on adjacent books may be read by mistake.
1 mark for one valid disadvantage.
Q2Direct data entry devices (bar codes, RFID, QR) · Core · Paper 1 style · 4 marks
(a)Write down the direct data entry device that is most suitable for each task.(i) Reading the account and cheque numbers printed in special ink at the bottom of a bank cheque.(ii) Reading pencil marks on 2000 multiple-choice answer sheets in a school.(iii) Reading the strip on the back of an old-style hotel room key card.(iv) Reading the price label on a packet of biscuits at a supermarket checkout.[4]
Show answer
(a)(i) Magnetic ink character reader (MICR)(ii) Optical mark reader (OMR)(iii) Magnetic stripe reader(iv) Bar code reader/scanner
1 mark for each correct device. Brand names not accepted.
Q3Direct data entry devices (bar codes, RFID, QR) · Core · Paper 1 style · 4 marks
(a)Describe the steps that take place when a cashier scans the bar code on a tin of beans at a supermarket checkout.[4]
Show answer
(a) The reader shines (red/laser) light on the bar code; the light is reflected from the white spaces, not the black bars; the reflections are converted into a number (product code); the code is looked up in the stock database/file; the price and description are sent back to the till and shown/printed on the receipt; the stock level for the item is reduced by 1.
1 mark per step, max 4.
Q4Direct data entry devices (bar codes, RFID, QR) · Standard · Paper 1 style · 6 marks
(a)A warehouse in Karachi stores boxes of spare parts. It is deciding whether to label the boxes with bar codes or with RFID tags. Compare the use of bar code readers and RFID readers for identifying the boxes.[6]
Show answer
(a) Similarities and differences written as linked comparisons, e.g. both read data without typing so reduce errors; both identify the box and look up its record in the stock file. RFID reads by radio waves while a bar code reader uses light reflected from the code; RFID needs no line of sight but a bar code must face the reader; RFID can read many boxes at once whereas bar codes are scanned one at a time; RFID tags can be read from further away; RFID tag data can be rewritten but a printed bar code cannot be changed; RFID tags cost more than printed labels; bar codes are easily damaged/dirtied, RFID tags are more robust.
1 mark per valid point, max 6. At least one similarity needed for full marks. Points must compare the two (e.g. 'RFID…whereas bar code…'); a list of separate features in two columns max 4.
Q5Direct data entry devices (bar codes, RFID, QR) · Standard · Paper 1 style · 6 marks
(a)A museum in Istanbul places a QR code next to each exhibit. Describe how a visitor uses the QR code to see more information about an exhibit.[3]
(b)Give two advantages to the museum of using QR codes rather than printed information boards.[2]
(c)Give one disadvantage of QR codes for visitors.[1]
Show answer
(a) Visitor opens the camera/QR app on their smartphone; points the camera at the QR code; the app decodes the pattern (into a URL/text); the phone opens the web page/shows the information or plays a video/audio guide.
1 mark each for any three steps in a sensible order.
(b) Any two, e.g. information can be updated online without reprinting; can link to video/audio/multiple languages; QR code takes very little wall space; cheap to produce; can store more data than a bar code.
1 mark each for any two.
(c) Any one, e.g. visitor needs a smartphone with a camera; needs internet access/mobile data to open the page; a QR code can be replaced by a fake one linking to a malicious site.
1 mark.
Q6Direct data entry devices (bar codes, RFID, QR) · Standard · Paper 1 style · 5 marks
(a)A national survey in Pakistan uses printed forms. Part of each form has answer boxes that people shade in with a pencil. Another part asks people to write their address in capital letters. Explain why an optical mark reader (OMR) is used for the shaded boxes.[2]
(b)Explain why the addresses are read using a scanner with optical character recognition (OCR) software and not an OMR.[2]
(c)State one disadvantage of using OCR to read the addresses.[1]
Show answer
(a) OMR detects the position of the marks in set positions; very fast so thousands of forms are processed quickly; more accurate than a person typing the answers.
1 mark for how it works/what it detects, 1 mark for a linked benefit.
(b) OMR can only detect whether a box is shaded, not read letters; OCR converts the scanned image of the handwriting/characters into editable text that can be stored in the database.
1 mark for why OMR is unsuitable, 1 mark for what OCR does.
(c) Handwriting may be unclear so characters are misread/errors need checking; poor-quality forms are rejected.
1 mark.
Q7Direct data entry devices (bar codes, RFID, QR) · Standard · Paper 1 style · 5 marks
(a)A customer in a restaurant in Dubai pays by inserting a chip and PIN card into a hand-held card reader. Describe the steps involved in making this payment.[5]
Show answer
(a) The waiter enters the amount; the card is inserted into the reader; the customer types the PIN on the keypad; the PIN is checked against the one stored on the chip; if correct, the card details are sent to the bank (securely/encrypted); the bank checks the account has enough funds; the payment is authorised and the money is transferred; the reader displays 'approved' and a receipt is printed; if the PIN is wrong the transaction is rejected (after limited attempts card locked).
1 mark per valid step in order, max 5.
Q8Direct data entry devices (bar codes, RFID, QR) · Challenge · Paper 1 style · 6 marks
(a)A café in Islamabad accepts contactless card payments for amounts up to a set limit. Describe how a contactless payment is made.[4]
(b)Explain two security concerns about contactless payments.[2]
Show answer
(a) Total is entered on the card reader/till; customer holds the card (or phone) close to the reader; data is sent by radio waves (RFID/NFC) from the chip; the transaction is encrypted; the card details are checked with the bank and the payment is authorised; reader shows that the payment is accepted (beep/green light) and a receipt can be given. No PIN is needed below the limit.
1 mark per point, max 4.
(b) Any two explained, e.g. a stolen card can be used without knowing the PIN (up to the limit); a criminal with a hidden reader close by could read card data (skimming/eavesdropping); a customer might pay twice by mistake if the card is near the reader again.
1 mark each for any two explained concerns.
Q9Direct data entry devices (bar codes, RFID, QR) · Challenge · Paper 1 style · 6 marks
(a)A dairy farm near Sahiwal puts a passive RFID tag in each cow's ear. Describe how the reader obtains the data from a passive RFID tag.[3]
(b)Explain three reasons why RFID tags are more suitable than bar code labels for identifying the cows.[3]
Show answer
(a) The reader sends out radio waves; the tag's antenna picks up the radio signal, which provides the energy to power the tag (no battery); the tag sends back its stored data (unique ID) as radio waves; the reader receives the data and passes it to the computer (where the cow's record is looked up).
1 mark per point, max 3.
(b) Cows move, and RFID needs no line of sight so the cow does not need to be held still; many cows can be read at once as they pass through a gate; a tag works when covered in mud/dirt whereas a bar code would become unreadable; tags are tough/waterproof; data on the tag (e.g. vaccination date) can be updated.
1 mark for each explained reason, max 3.
Q10Direct data entry devices (bar codes, RFID, QR) · Challenge · Paper 1 style · 6 marks
(a)An international airport is planning to attach RFID tags to all checked-in luggage instead of using printed bar code labels. Evaluate this plan.[6]
Show answer
(a) Benefits: bags read automatically as they pass on conveyors without line of sight, so fewer lost/misrouted bags; many bags read at once speeds up sorting; tags readable at longer range and when label is creased/torn; passengers could track bags; data can be updated along the route. Drawbacks: tags cost more per bag than paper labels; all airports on the route need RFID readers or bags still need bar codes; radio signals can be blocked by metal/liquids in bags; tags may be read by unauthorised readers (privacy); setup costs of new readers and staff training. Conclusion with a justified judgement.
Level marking: 5–6 marks: benefits and drawbacks both well developed with a reasoned conclusion; 3–4 marks: both sides with some development; 1–2 marks: one side or list-like points. Up to 1 mark per developed point, max 6.
Q11Input devices · Core · Paper 1 style · 4 marks
(a)Write down the most suitable input device for each task.(i) A journalist recording a spoken interview to be stored on a laptop.(ii) A passenger selecting a destination on a ticket machine at a railway station.(iii) A pilot in training controlling a flight simulator.(iv) A student copying a printed photograph into a school magazine file.[4]
1 mark each. Accept keypad for (ii); do not accept mouse.
Q12Input devices · Core · Paper 1 style · 3 marks
(a)A teacher in Peshawar wants to put copies of her printed worksheets on the school website. Name the input device she should use.[1]
(b)She uses optical character recognition (OCR) software with this device. Give two advantages of using OCR software instead of retyping the worksheets.[2]
Show answer
(a) Scanner (flatbed scanner).
1 mark.
(b) Any two, e.g. faster than retyping; text can then be edited in a word processor; fewer typing errors; text can be searched; text can be converted to other formats/read aloud.
1 mark each.
Q13Input devices · Core · Paper 1 style · 3 marks
(a)State how a television remote control sends instructions to the television.[1]
(b)Give two uses of a driving wheel as an input device.[2]
Show answer
(a) By infrared signals (accept Bluetooth/radio for some models).
1 mark.
(b) Any two, e.g. driving games; driving simulators for learner drivers; training lorry/bus drivers; remote control of model cars/drones.
1 mark each.
Q14Input devices · Standard · Paper 1 style · 4 marks
(a)A fast-food restaurant in Lahore installs touch screens so that customers can place their own orders. Explain two advantages of using touch screens for this purpose.[2]
(b)Explain two disadvantages of using touch screens for this purpose.[2]
Show answer
(a) Any two explained, e.g. easy to use by selecting pictures/icons so little training needed; no separate keyboard/mouse that can be stolen or damaged; options limited to the menu, so fewer input errors; can be cleaned/wiped easily; faster for customers so queues are shorter.
1 mark each for an advantage with a reason.
(b) Any two explained, e.g. screens get dirty/greasy and need regular cleaning (hygiene); limited options compared with a keyboard for special requests; screens can be scratched or cracked; people with poor eyesight/disabilities may find them hard to use; arm fatigue if used for a long time.
1 mark each.
Q15Input devices · Standard · Paper 1 style · 4 marks
(a)A doctor in a clinic is choosing between a keyboard and a microphone with speech recognition software to enter patient notes. Compare these two input methods for this task.[4]
Show answer
(a) Both enter text into the patient record. A microphone is faster/hands-free so the doctor can examine the patient while speaking, whereas typing needs both hands; speech recognition may misrecognise medical words/accents and needs training, while typing is more accurate for unusual words; background noise in a busy clinic affects the microphone but not a keyboard; speaking aloud may let others hear confidential details, whereas typing is private; a keyboard is cheap and familiar.
1 mark per valid comparison point, max 4. Points must compare the two methods.
Q16Input devices · Standard · Paper 1 style · 4 marks
(a)A power station control room uses trackerballs instead of mice. Describe what a trackerball is.[2]
(b)Explain two reasons why trackerballs are suitable for the control room.[2]
Show answer
(a) A pointing device with a ball on top that the user rolls with the fingers/thumb/palm; the device itself stays still, and buttons are used to click/select.
1 mark for the rolled ball, 1 mark for staying stationary/buttons.
(b) Any two, e.g. needs less desk space because the device does not move; can be fixed into the control desk so it cannot be knocked off/stolen; easier for people with limited hand/wrist movement; more accurate control of the pointer for fine positioning.
1 mark each for an explained reason.
Q17Input devices · Challenge · Paper 1 style · 6 marks
(a)A fashion designer in Faisalabad currently draws designs with a mouse. Discuss the benefits and drawbacks of using a graphics tablet instead of a mouse.[6]
Show answer
(a) Benefits: pen/stylus is held like a pencil so drawing is more natural and accurate; pressure sensitivity gives thicker/thinner lines; fine detail is easier; less strain on the wrist than gripping a mouse for long periods; hand-drawn designs can be traced. Drawbacks: more expensive than a mouse; takes time to learn because the hand moves on the tablet while looking at the screen; takes up more desk space; stylus can be lost; not as good for general tasks such as clicking menus. Conclusion, e.g. worthwhile for a designer who draws all day.
Up to 1 mark per developed point, max 4 for one side only; 6 marks needs both sides and a conclusion.
Q18Input devices · Challenge · Paper 1 style · 5 marks
(a)Explain why ATMs use a numeric keypad rather than a full keyboard.[2]
(b)Describe two problems customers may have when using the numeric keypad at an ATM.[2]
(c)Suggest one feature of the keypad that helps a customer who is blind or partially sighted.[1]
Show answer
(a) Only numbers are needed (PIN, amount), so a small keypad is enough; it is smaller, tougher and easier to make weatherproof/vandal-proof; fewer keys means faster and fewer errors.
1 mark each for any two explained points.
(b) People nearby can watch the PIN being typed (shoulder surfing); keys are small, so people with large fingers or poor eyesight can press the wrong key; keypads can be fitted with fake overlays to record PINs; hard to use in bright sunlight.
1 mark each.
(c) A raised dot on the 5 key / braille on keys; or a headphone socket for spoken instructions; large high-contrast keys.
1 mark.
Q19Sensors, actuators and ADC/DAC · Core · Paper 1 style · 4 marks
(a)Name the type of sensor that is most suitable for each use.(i) Checking whether the soil in a greenhouse is too dry.(ii) Turning street lights on automatically at dusk.(iii) Detecting a person entering a room in a burglar alarm system.(iv) Checking how acidic the water is in a river near a factory.[4]
Show answer
(a)(i) Moisture sensor(ii) Light sensor(iii) Infrared (motion) sensor (accept pressure sensor under a mat, acoustic/sound sensor)(iv) pH sensor
1 mark each.
Q20Sensors, actuators and ADC/DAC · Core · Paper 1 style · 3 marks
(a)State what is meant by an actuator.[1]
(b)Give two examples of actuators used in a home.[2]
Show answer
(a) A device that converts a signal from a computer/microprocessor into physical action/movement (or other output such as heat).
1 mark.
(b) Any two, e.g. motor (in a fan, washing machine, automatic gate); pump; heater (element); solenoid/valve (in a water tap or door lock); buzzer.
1 mark each.
Q21Sensors, actuators and ADC/DAC · Standard · Paper 1 style · 4 marks
(a)A computer controls the temperature in a greenhouse. A temperature sensor sends readings to the computer. Explain why an analogue-to-digital converter (ADC) is needed.[2]
(b)The computer opens a window using a motor. Explain why a digital-to-analogue converter (DAC) may be needed and name the type of device that the motor is.[2]
Show answer
(a) The sensor produces analogue data (continuously varying voltage); the computer can only process digital (binary) data, so the readings must be converted.
1 mark for sensor output analogue, 1 mark for computer needs digital.
(b) The computer's digital signal must be converted to an analogue signal/voltage to drive the motor; the motor is an actuator.
1 mark for DAC reason, 1 mark for actuator.
Q22Sensors, actuators and ADC/DAC · Standard · Paper 1 style · 4 marks
(a)A shopping centre car park has an automatic barrier that rises when a car drives up to it. Name a suitable sensor to detect the car.[1]
(b)Describe the role of an actuator in this system.[2]
(c)Explain why the sensor does not control the barrier by itself.[1]
Show answer
(a) Pressure sensor (in the road) / proximity sensor / magnetic field sensor / infrared sensor.
1 mark.
(b) The microprocessor sends a signal to the actuator; the actuator (motor) converts the signal into movement to raise and lower the barrier.
1 mark for receiving signal from the processor, 1 mark for producing movement.
(c) A sensor only measures/detects and sends data; a microprocessor must compare the data with stored values and decide what to do.
1 mark.
Q23Sensors, actuators and ADC/DAC · Challenge · Paper 1 style · 4 marks
A scientist leaves a temperature sensor connected to a data logger beside a glacier in Gilgit-Baltistan. The logger takes one reading every 30 seconds for 6 hours. Each reading is stored using 2 bytes.
(a)Calculate the number of readings taken.[1]
(b)Calculate the storage space needed for the readings, in bytes.[1]
(c)Give two reasons why a data logger is used instead of a person taking the readings.[2]
Show answer
(a) 720 readings
6 × 60 × 60 ÷ 30 = 720
(b) 1440 bytes
720 × 2 = 1440
(c) Any two, e.g. readings are taken at exact equal intervals; works in dangerous/very cold conditions; can run day and night without breaks; readings are more accurate (no human error); readings are stored automatically ready for analysis.
1 mark each.
Q24Sensors, actuators and ADC/DAC · Challenge · Paper 1 style · 6 marks
(a)A farm in Faisalabad uses a computerised irrigation system. Moisture sensors are placed in the soil and a pump supplies water. Describe how the system uses the sensors, conversion and actuator to keep the soil at the right moisture level.[6]
Show answer
(a) Moisture sensor continuously measures the soil moisture; readings are analogue and sent to an ADC which converts them to digital; the microprocessor compares the reading with a pre-set value stored in memory; if the reading is below the pre-set value the processor sends a signal (through a DAC) to the actuator to switch on the pump/open a valve; if the reading is at or above the pre-set value the pump is switched off/valve closed; the process repeats continuously in a loop.
1 mark per correct point in a logical order, max 6. Do not credit 'the sensor turns on the pump'.
Q25Output devices · Core · Paper 1 style · 4 marks
(a)Write down the most suitable output device for each task.(i) Printing 600 report cards in a school office in one afternoon.(ii) Printing one high-quality colour photograph at home.(iii) Making a plastic model of a replacement part for a bicycle.(iv) Playing train announcements to passengers on a platform.[4]
Show answer
(a)(i) Laser printer(ii) Inkjet printer(iii) 3D printer(iv) Speakers
1 mark each.
Q26Output devices · Core · Paper 1 style · 4 marks
(a)A teacher in Multan uses a multimedia projector in her classroom. Give two advantages of using a projector instead of a large monitor.[2]
(b)Give two disadvantages of using a projector.[2]
Show answer
(a) Any two, e.g. produces a very large image so the whole class can see; cheaper than a monitor of the same size; portable/can be moved between rooms; can project onto an interactive whiteboard.
1 mark each.
(b) Any two, e.g. image is less clear in a bright room; bulb/lamp is expensive and may fail; fan can be noisy; people walking in front cast shadows; needs setting up/focusing.
1 mark each.
Q27Output devices · Standard · Paper 1 style · 6 marks
(a)A small accounting office in Islamabad prints about 3000 pages of black-and-white letters and invoices each week. Compare laser printers and inkjet printers for this office.[6]
Show answer
(a) Both are non-impact printers that print text and graphics from the computer on plain paper. Laser printers are faster than inkjet printers, which suits large volumes; laser toner cartridges print many more pages than ink cartridges so cost per page is lower; laser output does not smudge, whereas inkjet ink can smudge while wet; inkjet printers are cheaper to buy; laser printers are larger and produce ozone/toner particles; inkjet printers are better for high-quality photographs; laser paper trays hold more paper. Conclusion: laser more suitable for this office.
1 mark per comparison point, max 6. At least one similarity needed for full marks.
Q28Output devices · Standard · Paper 1 style · 5 marks
(a)Describe how a 3D printer produces a solid object.[3]
(b)Give two uses of 3D printers in medicine.[2]
Show answer
(a) A design is created with CAD software/file; the software slices the design into thin layers; the printer builds the object one layer at a time (additive manufacturing) from material such as plastic/resin/powder; each layer is melted/bonded or hardened onto the layer below.
1 mark per point, max 3.
(b) Any two, e.g. prosthetic limbs; artificial joints/implants; dental crowns/braces; models of organs for surgeons to practise on; tissue engineering; medical tools/splints.
1 mark each.
Q29Output devices · Standard · Paper 1 style · 4 marks
(a)State whether each device is an input device, an output device, or both.(i) Touch screen(ii) Actuator(iii) Light sensor(iv) 3D printer(v) Microphone(vi) Multimedia projector[3]
(b)Explain why a touch screen can be described as both an input device and an output device.[1]
All six correct: 3 marks; four or five correct: 2 marks; two or three correct: 1 mark.
(b) It displays information/images to the user (output) and detects where the user touches the screen to make selections (input).
1 mark for both roles.
Q30Output devices · Challenge · Paper 1 style · 6 marks
(a)Describe the steps a laser printer goes through to print a page.[5]
(b)Explain why a laser printer is suitable for printing a large number of copies of the same page.[1]
Show answer
(a) The page data is sent to the printer and stored in its memory/buffer; the drum is given a (positive) electrostatic charge; a laser beam scans the drum, removing the charge where the image will be (or vice versa), forming an electrostatic image; the drum is coated with charged toner, which sticks only to the charged/image areas; the paper is given an opposite charge and the toner is transferred to it as it passes the drum; the fuser heats and presses the toner so it melts onto the paper; the drum is discharged/cleaned for the next page.
1 mark per step, max 5.
(b) The whole page image is formed on the drum at once so pages are printed very quickly/the toner lasts for many pages.
1 mark.
Similar questions
Questions that test the same subtopic in different years, grouped so you can work on one skill at a time.
References only: find each question in its paper (official link where available, otherwise through your school).
Direct data entry devices (bar codes, RFID, QR)7 questions · 6/9 sessions
