Digital Circuits Questions and Answers – Liquid Crystal Displays

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This set of Digital Electronics/Circuits Multiple Choice Questions & Answers (MCQs) focuses on “Liquid Crystal Displays”.

1. The full form of LCD is ____________
a) Liquid Crystal Display
b) Liquid Crystalline Display
c) Logical Crystal Display
d) Logical Crystalline Display
View Answer

Answer: a
Explanation: The full form of LCD is “Liquid Crystal Display”. They provide thinner displays as compared to Cathode Ray Tubes.

2. The optical properties of liquid crystals depend on the direction of ___________
a) Air
b) Solid
c) Light
d) Water
View Answer

Answer: c
Explanation: The optical properties of liquid crystals depend on the direction of light travels through a layer of the material.

3. By which properties, the orientation of molecules in a layer of liquid crystals can be changed?
a) Magnetic field
b) Electric field
c) Electromagnetic field
d) Gallois field
View Answer

Answer: b
Explanation: In LCD, the electric field is induced by a small electric voltage applied across it; Due to which the orientation of molecules in a layer of liquid crystals can be changed.
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4. Electro-optical effect is produced in ___________
a) LED
b) LCD
c) OFC
d) OLED
View Answer

Answer: b
Explanation: An electric field (induced by a small electric voltage) can change the orientation of molecules in a layer of liquid crystal and thus affect its optical properties. Such a process is termed an electro-optical effect, and it forms the basis for LCDs.

5. The direction of electric field in an LCD is determined by ___________
a) the molecule’s chemical structure
b) Crystalline surface structure
c) Molecular Orbital Theory
d) Quantum Cellular Automata
View Answer

Answer: a
Explanation: For LCDs, the change in optical properties results from orienting the molecular axes either along or perpendicular to the applied electric field, the preferred direction being determined by the details of the molecule’s chemical structure.

6. The first LCDs became commercially available in ___________
a) 1950s
b) 1980s
c) 1960s
d) 1970s
View Answer

Answer: c
Explanation: The first LCDs became commercially available in the late 1960s and were based on a light-scattering effect known as the dynamic scattering mode.

7. LCDs operate from a voltage ranges from ___________
a) 3 to 15V
b) 10 to 15V
c) 10V
d) 5V
View Answer

Answer: a
Explanation: LCDs operate from a voltage ranges from 3 to 15V rms. They provide thinner displays as compared to Cathode Ray Tubes.
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8. LCDs operate from a frequency ranges from ___________
a) 10Hz to 60Hz
b) 50Hz to 70Hz
c) 30Hz to 60Hz
d) None of the Mentioned
View Answer

Answer: c
Explanation: LCDs operate from a frequency ranges from 30Hz to 60Hz. LCDs operate from a voltage ranges from 3 to 15V rms. They provide thinner displays as compared to Cathode Ray Tubes.

9. In 7 segment display, how many LEDs are used?
a) 8
b) 7
c) 10
d) 9
View Answer

Answer: b
Explanation: There are 7 LEDs used in a 7 segment display. 7 segment displays are used for displaying decimal numerals which are comparatively convenient to dot matrix displays.
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10. What is the backplane in LCD?
a) The ac voltage applied between segment and a common element
b) The dc voltage applied between segment and a common element
c) The amount of power consumed
d) For adjusting the intensity of the LCD
View Answer

Answer: a
Explanation: The ac voltage applied between the segment and a common element is called the backplane(bp). In which each segment is driven by an EX-OR gate.

Sanfoundry Global Education & Learning Series – Digital Circuits.

To practice all areas of Digital Circuits, here is complete set of 1000+ Multiple Choice Questions and Answers.

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Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

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