UPSC Prelims 2008 Q111: Science & Technology – Physics

UPSC Prelims 2008, General Studies Paper I · Science & Technology

Which one of the following laser types is used in a laser printer?

Answer: (c) Semiconductor laser

Explanation

Which laser type is used in laser printers

Laser printers rely on a specific, compact type of laser technology for their printing mechanism.

Option	Verdict	Reason
(a) Dye laser	Incorrect	Not the type used in laser printers
(b) Gas laser	Incorrect	Also not the type used in laser printers
(c) Semiconductor laser	Correct	Laser printers use a compact, efficient semiconductor laser (laser diode) to create the printed image on the photosensitive drum
(d) Excimer laser	Incorrect	Not the type used in laser printers

Laser printer technology facts:

Point	Detail
Laser type	Semiconductor laser (laser diode)
Function	Creates the image pattern on the printer's photosensitive drum

Answer: (c) Semiconductor laser.

Laser printers use a SEMICONDUCTOR LASER (laser diode) to create the image pattern on the photosensitive drum.

Semiconductor laser: the type used in laser printers.

Confusing the compact semiconductor laser used in printers with other, larger laser types (gas, excimer, dye lasers).
Not knowing the specific laser diode technology behind everyday laser printers.
Assuming all laser applications use the same underlying laser type.

Laser printers = semiconductor laser (laser diode). A specific, everyday-technology laser-type fact.

NCERT Class XII Physics — Semiconductor Electronics (light-emitting diodes and laser diodes)
Encyclopaedia Britannica — laser printer