Theory
Why the bank buys the noisy one
A bank's purchase officer visits Chirag and, ignoring the sleek laser printers, orders three dot matrix printers, the loudest, oldest-looking machines in the shop.
You whisper: "Why would anyone choose that?"
Chirag: "Because it is the only printer here that can hit the paper."
That one word, hit, splits the entire printer world in two, and it is the first line of every exam answer on this topic.
Theory
Typewriter, spray can, photocopier
Three ways to put ink on paper: punch it through a ribbon like a typewriter (dot matrix), spray it in fine droplets like a micro spray-can (inkjet), or fuse powder onto the page with light and heat like a photocopier (laser). Punching touches the paper, impact. Spraying and fusing never touch it, non-impact.
At a glance
The three printers exams compare
| Printer | How it prints | Best at | Weakness |
|---|---|---|---|
| Dot matrix | Pins strike an inked ribbon | Carbon copies, cheap bulk bills | Noisy, rough print |
| Inkjet | Sprays microscopic ink droplets | Colour photos at home | Costly ink, nozzles clog |
| Laser | Toner fused by heat onto paper | Fast sharp office text | Costlier machine, dull photos |
Theory
Inside the laser printer
The laser's four-step dance is a favourite "explain the working" question:
- Charge: a rotating drum gets a uniform electric charge.
- Write: the laser beam draws your page onto the drum, discharging exactly where ink should go.
- Tone: powdered ink (toner) sticks only to the laser-written areas.
- Fuse: hot rollers press and melt the toner permanently onto the paper.
That warm sheet a laser printer hands you? Fresh from the fuser. The heat IS step four.
Quiz
A courier company prints delivery challans in triplicate: one impact creates three copies with carbon sheets between them. Which printer MUST they use?
- Dot matrix, only impact printers can press through carbon sheets
- Laser, because it is the fastest
- Inkjet, because ink soaks through three sheets
- Any printer works with carbon paper
Show the answer
Dot matrix, only impact printers can press through carbon sheets
Carbon copies need physical striking force passing through the sheet stack; only impact printers (dot matrix) provide it. Laser light and inkjet droplets touch just the top sheet, carbon paper stays blank under them. This carbon-copy question is the single most repeated printer exam item, and it is the bank's answer too.
Think first
Advise two customers
Customer A wants to print family photos occasionally at home. Customer B runs a coaching class printing 200 pages of sharp black-and-white notes daily. Match each to a printer, with the one-line reason.
Show the answer
A: inkjet, droplet spraying blends colours beautifully for photos, and low volume keeps ink costs bearable. B: laser, fast, crisp text at the lowest cost per page for bulk work; toner lasts thousands of pages. Swap them and both suffer: laser photos look flat, and inkjet cartridges would bankrupt the coaching class in a month.
Watch out
Where marks leak
Skipping the impact vs non-impact classification: examiners want it as the opening line (impact: dot matrix; non-impact: inkjet, laser). Giving carbon-copy powers to laser or inkjet: impossible, no strike. And in the laser working, order matters: charge → write → tone → fuse; students who forget fusing lose the step that actually fixes ink to paper.
Theory
Shop economics worth remembering
Chirag's buying rule for customers: machine price is not printer price. Inkjets are cheap to buy and expensive per page (ink is costlier than good perfume, per millilitre); lasers cost more upfront and pennies per page. Whenever you evaluate technology, in exams or in life, ask for the running cost, not just the sticker.
Summary
Key takeaways
- First classify: impact (dot matrix) vs non-impact (inkjet, laser).
- Dot matrix: pins strike a ribbon; noisy but prints carbon copies, still used by banks.
- Inkjet: sprayed droplets; colour photos at home; costly ink, clogging nozzles.
- Laser: charge → write → tone → fuse; fast, sharp, cheapest per page in bulk.
- Match printer to workload; count running cost, not sticker price.
- Memory hook: punch it, spray it, or fuse it.