Display Technologies MCQs: 12 Solved CRT, LCD and Raster Questions

Display-technology MCQs mix four vocabularies in the same options: geometry such as aspect ratio and resolution, CRT beam control, phosphor behaviour, and LCD light modulation. Remembering only device names is not enough because you must separate the physical action from the component that performs it. These 12 solved questions test recognition and elimination across geometry, CRT operation, phosphor behaviour, raster scanning and LCD layers. Choose each answer before reading the explanation, then use the UGC NET CS Exam Preparation page for the broader exam route.

Fix the display vocabulary before solving

Questions 1-2: aspect ratio and resolution

Question 1

UP LT Grade, 2021

Aspect ratio is the ratio of _____ to _____.

• A. Height; width

• B. Width; height

• C. Diagonal; height

• D. Height; diagonal

Answer: B. Width; height

Aspect ratio is width divided by height: 1280:720 = 16:9. A is the reciprocal; C and D wrongly use the diagonal. Worked solution.

Question 2

UP LT Grade, 2021

The maximum number of points that can be displayed without overlap on a CRT is referred to as ______.

• A. persistence

• B. resolution

• C. aspect ratio

• D. phosphorescence

Answer: B. resolution

Resolution names distinguishable points without overlap. Aspect ratio describes shape; persistence and phosphorescence concern light over time. Worked solution.

Questions 3-5: CRT parts, beam intensity and retrace

Question 3

UGC NET, 2015

Which of the following are components of a CRT?

• (a) Electron gun

• (b) Control electrode

• (c) Focusing electrode

• (d) Phosphor-coated screen

Codes:

• A. (a) and (d)

• B. (a), (b) and (d)

• C. (a), (b), (c) and (d)

• D. (a), (c) and (d)

Answer: C. (a), (b), (c) and (d)

The gun supplies electrons, the control electrode modulates current, the focusing electrode narrows the beam, and the phosphor-coated screen emits light. All four belong. Worked solution.

Question 4

UP LT Grade, 2021

Which component of CRT regulates the intensity of the electron beam?

• A. Heating Filament

• B. Accelerating Anode

• C. Focusing Anode

• D. Control Grid

Answer: D. Control Grid

The filament heats, the accelerating anode changes speed, and the focusing anode shapes the beam. The control grid regulates current and therefore spot intensity. Worked solution.

Question 5

UGC NET, 2017

With respect to CRT, the horizontal retrace is defined as :

• A. The path an electron beam takes when returning to the left side of the CRT.

• B. The path an electron beam takes when returning to the right side of the CRT.

• C. The technique of turning the electron beam off while retracing.

• D. The technique of turning the electron beam on/off while retracing.

Answer: A. The path an electron beam takes when returning to the left side of the CRT.

Scanning goes left to right; horizontal retrace is the right-to-left return. Blanking may switch the beam off then, but it is an action, not retrace itself. Worked solution.

Questions 6-8: phosphor light and colour CRT methods

Question 6

UGC NET, 2025

The light given off by the phosphor during exposure to the electron beam is known as

• A. Fluorescence

• B. Phosphorescence

• C. Persistence

• D. Retracing

Answer: A. Fluorescence

Fluorescence occurs during excitation. Phosphorescence is afterglow, persistence is its useful duration, and retracing is beam motion. Time separates the first three terms. Worked solution.

Question 7

UP LT Grade, 2022

In shadow mask CRT, each pixel emits ______ lights.

• A. Black and White

• B. Blue, Green, Red

• C. Blue, Green, White

• D. Green, Red, Black

Answer: B. Blue, Green, Red

The mask aligns beams with red, green, and blue phosphors. Their intensities combine into colours. Black is no emission; white is a combined result. Worked solution.

Question 8

UGC NET, 2014

Beam-penetration and shadow-mask are the two basic techniques for producing colour displays with a CRT. Which of the following is not true?

• I. Beam penetration is used with random-scan monitors.

• II. Shadow mask is used in raster-scan systems.

• III. The beam-penetration method is better than the shadow-mask method.

• IV. The shadow-mask method is better than the beam-penetration method.

• A. I and II

• B. II and III

• C. III only

• D. IV only

Answer: C. III only

I correctly pairs beam penetration with random scan; II pairs shadow mask with raster scan. Under the comparison intended by the item, colour range is the criterion: shadow-mask displays support many colours, while beam penetration supports only a small set. IV is true and III is false, making C the correct option. Worked solution.

Questions 9-10: raster scanning and memory-tube storage

Question 9

UGC NET, 2022

Assertion A: A Raster scan device is a CRT graphic device and can use a television monitor for display

Reason R: In Raster scan display the picture is composed of a series of dots. These dots are traced out as a series of horizontal lines. Television works in a similar fashion.

In the light of the above statements, choose the correct answer from the options given below:

• A. Both A and R are true and R is the correct explanation of A

• B. Both A and R are true but R is not the correct explanation of A

• C. A is true but R is false

• D. A is false but R is true

Answer: A. Both A and R are true and R is the correct explanation of A

Raster-scan CRTs form pictures from dots traced in horizontal lines, the same scan principle used by traditional television systems. The reason therefore explains the assertion, so A is correct. Worked solution.

Question 10

UGC NET, 2015

Which of the following are principal components of a memory-tube display?

• (a) Flooding gun

• (b) Collector

• (c) Phosphor grains

• (d) Ground

Codes:

• A. (a) and (b)

• B. (c) only

• C. (d) only

• D. All the above

Answer: D. All the above

The flooding gun supplies electrons, the collector gathers them, phosphor grains emit the output, and ground provides the reference or return. All four components belong, so D is correct. Worked solution.

Questions 11-12: LCD light modulation and layer matching

Question 11

UP LT Grade, 2023

LCD Panels or flat panel display uses the property of _____.

• A. Filter

• B. Thickness

• C. Light

• D. Size

Answer: C. Light

The liquid-crystal and polariser stack controls light transmission. Thickness and size are dimensions; filter names only one possible optical component, while light is the property being controlled. Worked solution.

Question 12

UGC NET, 2017

Match the following:

List I	List II
a. Glass	i. Contains liquid crystal and serves as a bonding surface for a conductive coating
b. Conductive coating	ii. Acts as a conductor so that a voltage can be applied across the liquid crystal
c. Liquid crystal	iii. A substance that polarises light when voltage is applied
d. Polarised film	iv. A transparent sheet that polarises light

Codes:

• A. a-i, b-ii, c-iii, d-iv

• B. a-i, b-iii, c-ii, d-iv

• C. a-iv, b-iii, c-ii, d-i

• D. a-iv, b-ii, c-i, d-iii

Answer: A. a-i, b-ii, c-iii, d-iv

Glass is the bonding substrate, the conductive coating carries voltage, liquid crystal changes optically under voltage, and polarised film polarises light. Thus a-i, b-ii, c-iii, d-iv, option A. Worked solution.

Common traps, score check and the next practice step

Use this five-line error checklist:

• Never invert width:height.

• Do not use resolution as a synonym for physical screen size.

• Separate beam generation, speed, focus, and intensity.

• Separate fluorescence during excitation from afterglow and persistence.

• In assertion-reason items, establish that both statements are true, then test whether R explains A.

The score bands are study guidance, not official cutoffs. With 10-12 correct, move to mixed computer-graphics practice. With 7-9, redo the CRT or LCD family that caused errors. With 0-6, rebuild the table and re-solve after one day.

Revise through Computer Fundamentals for CS Teaching Exams. For broader subject priorities, use UGC NET Computer Science High-Yield Topics. NET learners can continue with NTA-UGC-NET Paper 2; DSSSB learners can use DSSSB TGT Computer Science 2026 Section B. Choose your route, then solve the set without looking at the answers.