NMPHS SAPERU
(REVISION)
Chapter 1
Digital Literacy (advanced)
Q.1. What do you mean by overhead Projector?
Ans: A projector is capable of projecting enlarged images of written or pictorial material onto a screen or wall. An overhead projector is a very basic but reliable tool used to display images onto a screen or wall. It consists of a large box containing a cooling fan and an extremely bright light, with a long arm extended above it.
OHP
Q. 2. What are the main parts of an overhead projector (OHP)? Ans: An overhead projector has following parts
1. LAMP and Reflector
2. Blower
3. Base Mirror
4. Projection stage
5. Upper section.
Q. 3. How can you handle overhead projectors?
Ans: steps to handle overhead projectors:
1. Cover the transparency when you are done.
2. Bring spare bulbs and a glove to change the bulb.
3. Place you overhead projector on a table so it does not block you or the screen.
4. You need to consider is to keep the cleanliness of your lens Q . 4. Define Digital Screen.
Ans: Digital Screen is a display device for presentation of images, text, or video transmitted electronically, without producing a permanent record. It include television sets, computer monitors etc.
Q.5 What is LED? Explain.
Ans: LED stands for Light emitting diodes. It is a two-lead semiconductor light source. LED and LCD are liquid crystal displays. The basic technology is the same in that, both have two layers of polarized glass though which are liquid crystals both block and pass light. LED is a subset of LCD TVs. LED work with a color wheel RGB. – Colored lights (RED, green and blue) to produce more realistic and sharper colors.
Q. 6. What are the advantages, disadvantages and applications of LED? Ans: Advantages of LED:
1. LED’s are more superior in terms of picture quality
2. LED has a higher contrast ratio as compared to LCD monitor 3. LED’s are more superior in terms of picture quality
4. LED has a higher contrast ratio as compared to LCD monitor 3. Led helps save on energy as compared to LCD or CRT 4. Can be mounted on wall or panel
Disadvantages of LED:
1. Expensive as compared to LCD
2. Low Reliability
3. Speed is very low
Applications of LED:
1. LED is used as a bulb in the homes and industries.
2. LED’s are used in the motorcycles and cars.
3. Used in the mobile phones.
4. At the traffic light signals LED’s are used.
Q.7. What is LCD? What are Applications, advantages and disadvantages of LCD?
Ans: LCD stands for liquid crystal display is a flat, thin display device that has replaced the older CRT Display. LCD provides better picture quality and support for large resolutions. LCD displays are thinner and lighter than cathode ray tube(CRT) of similar display size. LCD consists of liquid crystals sandwiched in between transparent glass electrodes.
LCD
Applications of LED:
1. Liquid crystal technology has major applications in the field of science and engineering as well as on electronic devices. 2. Liquid crystal thermometer
3. Optical imaging
4. Used in the medical applications.
Advantages of LCD:
1. Compact and light weight
2. Can be mounted on wall or panel
3. Cost effective
4. Consume less energy and are more durable
5. Available in various sizes.
Disadvantages of LCD:
1. Require additional light sources.
2. Prices are more expensive compared to Plasma TV.
3. Response time is longer.
4. Backlight dims as the LCD ages.
Q.8. What do you mean by Plasma display? Explain.
Ans: Plasma technology is based on the fluorescent light bulb. A plasma display is a computer video display in which each pixel on the screen is
illuminated by a tiny bit of plasma or charged gas, somewhat like a tiny neon light. Plasma displays are thinner than cathode ray tube (CRT) displays and brighter than liquid crystal displays (LCD). A plasma display panel (PDP) is a type of flat panel display that uses small cells containing plasma: ionized gas that responds to electric fields.
Advantages
1. Better than CRT display.
2. More compact than CRT.
3. Better Contrast Ratios.
4. Wide Viewing Angle
5. Less visible motion blurs.
6. It offers high resolution.
7. It is slim and light in weight.
8. It can display 16.7 million colors.
9. It offers widescreen 16:9 ratio display.
Disadvantages
1. Flickering Effects.
2. More Expensive.
3. Uses more electrical power, on average, than an LCD TV. 4. Does not work as well at high altitudes above 6,500 feet (2,000 meters) due to pressure differential between the gases inside the screen and the air pressure at altitude. It may cause a buzzing noise. 5. Prices are very high.
6. They have shorter life span and there is no option to repair burnt out tube or backlight.
7. They have lower brightness levels.
8. Susceptibility to Degradation.
Q. 9. What do you mean by Fax Machine. Explain?
Ans: Fax machine is a device that sends and receives printed pages or images over telephone lines by digitizing the material with an internal optical scanner and transmitting the information as electronic signals.
The transmissions it sends are called "faxes" and these can be sent between two fax machines or between fax machine and computer.
It is basically used to transmit documents between locations. The majority of the time these are business documents.
Advantages of Fax Machine
1. Inexpensive- sending a message just at the cost of a telephone call. 2. They are simple to use and require very little training.
3. As long as the fax machine is switched on, messages can be received at any time day or night.
Disadvantages of Fax Machine
1. You might dial the wrong number and send your document to someone else.
2. If the receiving machine is busy your fax will not be delivered. 3. It can take a long time to transmit if you have many sheets of paper.
Uses of Fax Machine
1. Fax machines are used to transmit documents between locations. 2. Copying- A fax machine can also function as a photocopier.
Fax Machine
Q.10. What are the steps to sending fax.
Ans: Steps to sending fax:
1. The original document is scanned with a Fax machine 2. Fax machines process the contents
3. Converts it into a bitmap
4. Transmit it through telephone lines
Sending a fax
1. Turn on the fax machine
2. Insert you documents
3. Dial the fax number
4. Press send button
5. Wait for the document to finish transmitting.
Q. 11. What do you mean by Speakers?
Ans: Speakers are an output device. They receive audio input from the computer's sound card and produce audio output in the form of sound waves. It is used to listen sounds from computer. Speakers usually come in pairs, which allow them to produce stereo sound from two separate audio channels.
Speakers are in different shapes and sizes
Some speakers have equalization features such as bass and treble controls.
Advantages of Speakers
1. They help blind people.
2. Sound amplification (make it louder)
3. Very simple to operate
Disadvantages of Speakers
1. The output from speakers can disturb others.
2. High quality speakers are expensive
Speaker
Q.12. What is the difference between LCD, and CRT displays? Explain. Ans: Difference between LCD and CRT:
LCD | CRT |
LCD stands for Liquid crystal display. | CRT stands for Cathode ray tube |
LCD’s are much slimmer than CRT | The back size is bigger than the size of the monitor |
Sharp | Slightly less sharp images |
Lower power usage | Higher power usage |
LCD’s are free from the burn in issue | Suffers from burn in problem |
Perfect flat screen | In CRT only the outer glass that is flat and not the actual screen |
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Q.13 What is the difference between LED, LCD and CRT?
Ans: Difference between LED, LCD and CRT
LCD | LED | CRT or plasma |
Brightness is very poor in direct sunlight | Brightness is poor in bright light | Should be used in a dark place |
Contrast ratio 1000:1 Contrast ratio |
| Contrast ratio |
| 1000000:1 | 20000:1 |
Color is good | Good | Excellent |
LCD consume energy very low | Varies with brightness but usually lower than LCD | Varies with brightness but usually higher than LCD |
True/False :
1. Printers are only black and white. False
2. Laser printer is an electro static digital printer. True
3. The transmissions send by the fax machine are called faxes. True 4. Speakers receive audio input from the computer sound card. True 5. Overhead projector is used in class room. True
6. CRT is an old and almost outdated display screen. True
7. Plasma displays consume more electrical power than LED. True 8. Laser printer is type of impact printer. False
9. Inkjet printer is type of non-impact printer. True
10. Character printer is a noisy printer. True
11. LED stands for light emitting diodes. True
12. Overhead projector is an input device. False
13. LCD stands for Liquid crystal device. False
14. Speaker is a kind of input device. False
15. Plasma technology is based on the fluorescent light bulb. True 16. Dot matrix Printer is the fastest printer. False
17. Plotter is a kind of input device. False
18. Using fax, we can send copies of handwritten documents or documents with signatures. True
19. OHP stands for over head project. False
20. CRT stands for cathode ray tyre. False
21. Plasma displays are very light in weight. False
