Page 62 - Computer - 9(A&B)

inside it. These signals are sent to the CPU that interprets them to move the pointer accordingly on the screen. It
has 2 or 3 buttons which are used to move and select items on the screen.

Inside Mechanical Mouse Inside Optical Mouse
A mouse may be fi xed to the CPU box or may be wireless. Nowadays, optical mouse is used which has optical
sensors in it. This mouse uses LED or LASER technology to track the movement.

Scanner
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This input device is used to digitise pictures and documents that can be processed
by the computer. It works like a photocopier machine by projecting light on the Which type of scanners
image and measuring the light refl ected back with the help of optical sensors. The are generally used at our
amount of light, refl ected back tells the computer how much dark or light is the homes or in schools?
image at a particular point. Scanner can be of three types:

Flatbed Scanners
These scanners are used for high quality images. In these, picture to be scanned, is kept
on a fl at glass surface of scanner which is scanned in just one pass.

Hand Held Scanners
These are small in size and can be carried very easily in a hand. Because of the small sizes,
they cannot scan the entire image in one pass but multiple passes are used for scanning
the image.

Drum Scanners
These scanners are called roller fed scanners as, a roller or drum is rolled over the
picture to scan the image.

Joystick
This is another pointing device used to control the movement of the object on the screen. It
consists of a stick mounted on a spherical ball at its base which controls the movement of
object with the movement of stick. These are used to control gaming objects on the screen
and also for controlling the simulations. Because of its fl exible movement, it provides better
control than the arrow keys on the keyboard. They are often used to play video games and
computer games.
Gamepad

A gamepad is used while playing games. It is held in two hands and thumbs are used to
provide input.

Microphone

This input device is used to send sound input to the computer. It receives the sound waves
and converts them into electrical signals, i.e., into the digital format which can be processed
by the computer. In the computer, it is connected to the motherboard through a special
hardware, called sound card. It is used to record sounds, narrations, sound effects, etc.,
and also to work with the sound recognition system.

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