22 Learn, Revise & Practice ~ Computer Awareness
storing the documents in their original form that Some of the commonly used output devices are
can be modified and manipulated later on. described below
Scanner stores images in both gray scale and color
mode. The most common types of scanners are as Monitor
follows It is also known as Visual Display Unit (VDU). The
(i) Handheld scanners monitor is provided alongwith the computer to
(ii) Flatbed scanners view display the result.
(iii) Drum scanners An image on the monitor is created by a
configuration of dots, also known as pixels.
Microphone (Mic) A monitor is of two kinds; monochrome display
We can send input to the computer through a monitor and colour display monitor.
special manual input device called microphone or A monochrome display monitor uses only one
mic. A mic converts the received sound into colour to display text and colour display monitor
computer’s format, which is called Digitised can display 256 colours at a time.
Sound or Digital Audio.
The clarity of image depends on three factors which
To convert a voice into digital form, you need an
are as follows
additional hardware known as Sound Card. Sound
is used most often in multimedia. For example, we 1. Resolution of Screen Resolution refers to
can make our presentations more attractive using the number of pixels in horizontal and vertical
recorded narration, music or sound effects. directions. The resolution of a monitor is
higher when the pixels are closer together.
Now-a-days, microphones are also used with
speech recognition software. This means that we 2. Dot Pitch It refers to the diagonal distance
do not have to type, rather just have to speak and between two coloured pixels. The smaller the
the spoken words appear in our document. dot pitch, the better the resolution.
3. Refresh Rate The refresh rate of your display
Webcam (Web Camera) refers to how many times per second the
It is a video capturing device. Webcam is a digital display is able to draw a new image. The higher
camera attached to computer and can be used for the refresh rate, the more solid the image looks
video conferencing, online chatting, etc. on the screen. The refresh rate of monitor is
Webcam measured in Hertz (Hz).
The popular types of monitor are as follows
1. Cathode Ray Tube (CRT) It is a typical
rectangular shaped monitor that you see on a
desktop computer. The CRT works in a same
way as a television. CRT has a vacuum tube.
Webcam with Computer Webcam
The screen of CRT is covered with a fine layer
of phosphorescent elements, called phosphores.
Now-a-days, webcams are either embedded into
2. Liquid Crystal Display (LCD) These screens
the display with laptop/computer or connected via
are used in laptops and notebook sized PCs. A
USB or firewire port or Wi-Fi to the computer.
special type of liquid is sandwiched between
Output Devices two plates. It is a thin, flat and light weight
An output device is a piece of computer hardware screen made up of any number of color or
that receives data from a computer and then monochrome pixels arranged in front of a
translates that data into another form. That form light source.
may be audio, visual, textual or hard copy such as 3. Light Emitting Diode (LED) It is an electronic
printed document. device that emits light when electrical current
