← IGCSE Computer Science Paper 1

Comparing LCD and LED screens

LCD screens use a fluorescent (CCFL) backlight; LED screens use LED backlights, so they are brighter, thinner, have better contrast and use less power.

Part of: IGCSE Computer Science 0478 — 3.2 Input and Output Devices — Module 21

Understanding Comparing LCD and LED screens in IGCSE Computer Science Paper 1

What it does: LED backlights are smaller and use less power than CCFL tubes, so LED screens suit slim laptops. Older LCD screens are lit by a CCFL (cold cathode fluorescent lamp). LED screens use LEDs as the backlight. LED backlights can be brighter, so the picture is easier to see, even in a bright room. LED backlights can be controlled more precisely, so dark areas look darker and the contrast is better. An LED screen is thinner and uses less power, so it suits a portable device that runs on a battery. The CCFL backlight is the key feature of an LCD screen, which separates it from an LED screen.

Common mistakes: LED screens use less power than LCD screens because of their LED backlight. The line should be led_power = "low". An LED screen is backlit by LEDs. CCFL fluorescent tubes are the backlight in an LCD screen. The line should be backlight = "LED lights".

Class: _____________________  ·  Name: _____________________  ·  Date: _________

Free printable worksheet with full answer key — or add this module to a class and your students practise it interactively.

🖨 Print worksheet + answer key Add Comparing LCD and LED screens to a class →

This module's key terms are also in a printable crossword (Modules 262–272) and word search (Modules 262–282).

Take this worksheet further — free with Cloodit

Each concept is reinforced from every angle — learned, then applied, then tested.

Learning
Duo
Which backlight does an older LCD screen use?
A fluorescent (CCFL) backlightAn LED backlight
Matches
LED screen: backlight = CCFL
↓
LED screens use LED backlights, not CCFL tubes. CCFL is the backlight used in LCD screens.
Applying
Meanings
Term
LCD vs LED
Meaning
LCD screens use a fluorescent (CCFL) backlight; LED screens use LED backlights, so they are brighter, thinner, have better contrast and use less power.
Practice
LCD backlight: CCFL tube
Testing
Gaps
lcdBacklight ←
Check Answer
Spots
2led_backlight = "LED"
3led_power = "high"

Cloodit turns curriculum-aligned coding content into journeys students work through one biome at a time.

The 'Nautilus' badge — Default Expert, one of Cloodit's 106 collectible badges
Students earn collectable badges

Over 100 of them, across seven natural biomes.

Study Buddy
Students build a real study resource

Turns their work into revision material ready for Flash Cards and Exam study.

Diamond Dash — one of Cloodit's live, competitive Sprint games
Students lock in with Sprints

Live, competitive practice for the start of the lesson or a teacher-led lesson finisher.

A Cloodit certificate of achievement, ready to personalise and print
Custom printable certificates

Honour your top performers, or encourage a student who's trying hard — ready to print in seconds.

Add to class →

Quick Questions

1. Which backlight does an older LCD screen use?
A. An LED backlight
B. A fluorescent (CCFL) backlight ✓
Older LCD screens are lit by a CCFL (cold cathode fluorescent lamp). LED screens use LEDs as the backlight.
2. Which screen is usually thinner?
A. LED screen ✓
B. LCD screen with a CCFL backlight
LEDs are very small, so the backlight can be thin. A fluorescent tube needs more space, which makes the screen thicker.
3. Which screen normally uses less power?
A. LCD screen with a CCFL backlight
B. LED screen ✓
LED backlights use less electricity than fluorescent lamps. This also means less heat is produced.
4. Which screen usually gives a brighter picture?
A. LED screen ✓
B. LCD screen with a CCFL backlight
LED backlights can be brighter, so the picture is easier to see, even in a bright room.
5. Which screen usually has better contrast, such as deeper blacks?
A. LED screen ✓
B. LCD screen with a CCFL backlight
LED backlights can be controlled more precisely, so dark areas look darker and the contrast is better.

Match the Pairs

LCD backlight = CCFL → An LCD screen is lit from behind by a fluorescent (CCFL) tube backlight.
LED backlight = LEDs → An LED screen is lit by LEDs, so it is brighter and has better contrast.
A thin, light, battery-friendly laptop needs a screen that is slim and uses less power. → screen = LED
An older, thicker monitor that uses more power is likely to have a CCFL backlight. → screen = LCD
LED screen: backlight = CCFL → LED screens use LED backlights, not CCFL tubes. CCFL is the backlight used in LCD screens.
LED power use > LCD power use → LED screens use less power than LCD screens, so the comparison is the wrong way round.

Key Term

LCD vs LED
LCD screens use a fluorescent (CCFL) backlight; LED screens use LED backlights, so they are brighter, thinner, have better contrast and use less power.

Fill in the Blanks

1. lcdBacklight ← CCFL ledBacklight ← LED
Hint: Type the abbreviation for the fluorescent tube backlight that LCD screens use.
2. brightness(LED) > brightness(LCD)
Hint: Type the comparison operator showing that LED screens are brighter than LCD screens.
3. power(LED) < power(LCD)
Hint: Type the function name for the quantity where LED screens use less than LCD screens.
4. IF portable = TRUE THEN screen ← LED ENDIF
Hint: Type the screen type that is thinner and uses less power, so it suits a portable device.
5. thickness(LED) < thickness(LCD)
Hint: Type the screen type that is the thinner of the two.

Spot the Error

Question 1
A lcd_backlight = "CCFL"
B led_backlight = "LED"
C led_power = "high"
D lcd_power = "higher"
Line C — LED screens use less power than LCD screens because of their LED backlight. The line should be led_power = "low".
Question 2
A screen = "LED"
B backlight = "CCFL tubes"
C thin = True
Line B — An LED screen is backlit by LEDs. CCFL fluorescent tubes are the backlight in an LCD screen. The line should be backlight = "LED lights".
Question 3
A if screen == "LED":
B thickness = "thicker"
C else:
D thickness = "thicker"
Line B — LED backlights are small, so LED screens can be thinner than LCD screens. This line should set thickness = "thinner".
Question 4
A screen = "LCD"
B backlight = "CCFL"
C brightness = "lower"
D contrast = "better"
Line D — An LCD screen with a CCFL backlight has lower contrast than an LED screen. The line should be contrast = "lower".
Question 5
A lcd_backlight = "LED"
B led_backlight = "LED"
C print(lcd_backlight)
Line A — An LCD screen uses a fluorescent (CCFL) backlight, not an LED one. The line should be lcd_backlight = "CCFL".

Student with a class code? Join your class →