Input Devices

Hello students, welcome to Kwickprep. At a shop, the cashier beeps a packet and the price appears. You scan a QR code and pay in seconds. Both are input devices at work. Today we will learn what input devices do and meet the most common ones, including sensors.

Let us begin with the meaning. An input device is hardware that sends data or commands into a computer. It turns our actions, like a key press or a voice, into electrical signals. Inside, the computer understands only binary, which means zeros and ones. So input is the very first step of input, process and output.

There are many ways to give input, so devices are grouped by the kind of data. We type letters and numbers using a keyboard. We point and click using a mouse or touchpad. Scanners and webcams capture pictures and video. A microphone captures sound. Sensors give input automatically, with no person needed.

Let us start with the device you use most. The keyboard is the most common input device for text. Most keyboards use the qwerty layout, named after the first six letters on the top row. It has letter keys, number keys, function keys and arrow keys. Keys can also be combined as shortcuts, like control and C together to copy.

Next, the pointing devices. A mouse is a pointing device, which means it moves the pointer on the screen. A left click selects something, and a right click opens a menu of options. The scroll wheel moves a page up and down. On a laptop, the touchpad does the same job with your finger.

Three more devices capture the real world. A scanner turns a paper page into a digital image, like scanning a marksheet for a college form. A webcam captures live video, which we use in online classes and video calls. A microphone captures sound, for voice typing, calls and voice assistants.

Now, the devices you see at every shop. A barcode is a pattern of black and white lines printed on a product. The barcode reader shines light on it and reads the pattern of reflections. Pause and predict: does the barcode store the price? No, it only gives a product code. The shop's computer then looks up the name and price in its database.

A QR code is a newer, square version of a barcode. A barcode is a row of lines, while a QR code is a square grid of dots. A barcode stores data in one direction, but a QR code stores it in two directions. So a QR code holds much more, like a website link or a UPI payment address. A barcode needs a scanner, but any phone camera can read a QR code.

A touch screen is both an input and an output device. It shows output, and it takes your touch as input. A capacitive screen senses the tiny electric charge of your finger, so it is used in phones. A resistive screen senses pressure, so it works with a stylus or even gloves. Many ticket kiosks and ATMs use touch screens.

Last, sensors. A sensor is a device that measures something in the physical world, like heat or light. It gives input automatically, without anyone pressing a key. Often its data goes to a microcontroller, which is a tiny computer on one chip. Sensors are common in phones, cars, smart homes and farms.

Here are sensors you meet every day. A temperature sensor measures heat, so an air conditioner knows when to switch off. A light sensor measures brightness, so your phone screen adjusts itself. A motion sensor detects movement, like at automatic doors. A moisture sensor measures water in soil, so a farm pump can switch on. A fingerprint sensor reads the pattern of your finger to unlock a phone.

Let us revise what we learned today. Input devices send data and commands into the computer. The common ones are the keyboard, mouse, scanner, webcam and microphone. Barcode and QR readers give a code that the computer looks up. Touch screens do both input and output. Sensors give input automatically, without a person. At home today, list five input devices and name the data each one sends.