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NDA Physics · Modern Physics

Scientific Acronyms: Full Forms to Memorise

A short list of physics-and-technology acronyms whose full forms the NDA tests directly — LED, LASER, LIGO and a few common companions.

All Modern Physics notesNDA Physics strategy

Why this matters

Two PYQs, both pure recall of an acronym's expansion. There is nothing to derive — just memorise the full forms. LED (Light Emitting Diode) and LIGO (Laser Interferometer Gravitational-wave Observatory) have both appeared.

Concept 1 of 2

Device and optics acronyms — LED, LASER, LCD

Intuition

Everyday electronics carry physics acronyms. LED and LASER both involve light emission from controlled energy transitions. The NDA simply asks for the full form, so memorise the expansion exactly.

Definition

Common device/optics acronyms:

  • LED = Light Emitting Diode — a semiconductor that emits light when forward-biased.
  • LASER = Light Amplification by Stimulated Emission of Radiation.
  • LCD = Liquid Crystal Display.
  • CFL = Compact Fluorescent Lamp.
AcronymFull form
LEDLight Emitting Diode
NDA 2018 / 2021 — LED stands for Light Emitting Diode.
LASERLight Amplification by Stimulated Emission of Radiation
LCDLiquid Crystal Display
CFLCompact Fluorescent Lamp
LED = Light Emitting Diode. Note LASER's expansion turns on "Stimulated Emission".
Practice this conceptself-check · 4 quick reps

Try it yourself

What is the full form of LED?

Practice — Level 1 (4 reps)

Quick reps to lock in the method. Try each, then check.

  1. 1.
    Full form of LED?
  2. 2.
    Full form of LASER?
  3. 3.
    Full form of LCD?
  4. 4.
    Is an LED a semiconductor device?

From the bank · past-year question

Example 1Modern PhysicsEASY
The full form of LED is

[Q71 · Sep · 2018]

LED's D is DIODE, not Display

LED = Light Emitting DIODE (a semiconductor). LCD = Liquid Crystal DISPLAY. Do not let the similar look swap the D-words.

Concept 2 of 2

Big-science and research acronyms — LIGO, LASER, MASER

Intuition

Large research facilities and effects have long acronyms. LIGO is the gravitational-wave observatory; expand it carefully because each word is tested.

Definition

Research-facility / advanced-physics acronyms:

  • LIGO = Laser Interferometer Gravitational-wave Observatory — detected gravitational waves.
  • MASER = Microwave Amplification by Stimulated Emission of Radiation (the microwave cousin of the laser).
  • SONAR = Sound Navigation and Ranging (uses ultrasonic sound).
  • RADAR = Radio Detection and Ranging (uses radio waves).
AcronymFull form
LIGOLaser Interferometer Gravitational-wave Observatory
NDA 2019 — LIGO stands for Laser Interferometer Gravitational-wave Observatory.
MASERMicrowave Amplification by Stimulated Emission of Radiation
SONARSound Navigation and Ranging
RADARRadio Detection and Ranging
LIGO opens with LASER and ends with OBSERVATORY. RADAR uses radio waves; SONAR uses sound.
Practice this conceptself-check · 4 quick reps

Try it yourself

What does the acronym LIGO stand for?

Practice — Level 1 (4 reps)

Quick reps to lock in the method. Try each, then check.

  1. 1.
    Full form of LIGO?
  2. 2.
    Full form of SONAR?
  3. 3.
    Full form of RADAR?
  4. 4.
    LIGO uses what kind of beam to make its measurements?

From the bank · past-year question

Example 2Modern PhysicsEASY
LIGO stands for

[Q119 · Apr · 2019]

LIGO starts with LASER, not Light

The first word of LIGO is "Laser" (the interferometer fires laser beams), giving Laser Interferometer Gravitational-wave Observatory. Do not expand the L as "Light".

Summary — formulas & gotchas at a glance

A revision cheat-sheet for the formulas and gotchas above. Click any concept name to jump back to its full explanation.

Reference tables (2)

Device and optics acronyms — LED, LASER, LCD4 rows
AcronymFull form
LEDLight Emitting Diode
NDA 2018 / 2021 — LED stands for Light Emitting Diode.
LASERLight Amplification by Stimulated Emission of Radiation
LCDLiquid Crystal Display
CFLCompact Fluorescent Lamp
LED = Light Emitting Diode. Note LASER's expansion turns on "Stimulated Emission".
Big-science and research acronyms — LIGO, LASER, MASER4 rows
AcronymFull form
LIGOLaser Interferometer Gravitational-wave Observatory
NDA 2019 — LIGO stands for Laser Interferometer Gravitational-wave Observatory.
MASERMicrowave Amplification by Stimulated Emission of Radiation
SONARSound Navigation and Ranging
RADARRadio Detection and Ranging
LIGO opens with LASER and ends with OBSERVATORY. RADAR uses radio waves; SONAR uses sound.

Watch out for (2)

Drill every past-year question on this subtopic

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