Sure, smart speakers can play music just like regular speakers, but it’s their ability to answer questions and respond to commands that makes them almost magical. So how do they do that? Well the brains behind every smart speaker is its virtual assistant - like Alexa or Siri. And these silky-voiced know-it-alls are powered by speech recognition software (SRS).
SRS converts our language (your analogue voice) into language that computers can understand (digital data). It breaks down your digitized words into tiny segments and compares each component sound to the vast library of samples stored in its memory. So if you say ‘cat’, the SRS will hear c-a-t, then compare those sounds to millions of sound templates, and match the whole word to a furry creature with whiskers. Then it analyses the context of the word (your entire sentence) to work out what you want. The SRS doesn’t really consider your question then answer it. It’s simply delivering a pre-programmed response to the command it’s received. Which isn’t actual intelligence, but it is pretty clever.
At the heart of your microwave oven sits a magnetron – a clever piece of tech that converts electricity into super-short (hence ‘micro’) radio waves. So when you place a bowl of soup inside the oven and hit “start”, the magnetron blasts the liquid with microwave radiation. The energy contained in the radiation waves is absorbed by the food molecules and is converted into heat.
The bowl is rotated on a turntable to expose all areas more-or-less evenly to the radiation, and any microwaves that miss the food are bounced back off the reflective internal walls of the oven until their energy has been absorbed by the soup. Unlike conventional cooking methods which ‘leak’ heat into the surrounding air, microwave ovens convert almost all the energy they use into heat - so they’re super efficient!
Motion-activated burglar alarms and security lights
There are two types of motion sensors. ‘Active’ sensors continually send out ultrasonic sound waves which are reflected back by the surrounding environment. This enables the receiver unit to map out a clear picture of the device’s field of vision - just like bats that use echolocation to ‘see’ in the dark. So, when someone or something steps into the motion sensors’ line of ‘sight’, it recognises that the scene it’s watching has changed, and it activates the light or alarm.
Most household security lights use a PIR system, which stands for ‘passive infrared’. This type of device detects the infrared radiation given off by people and animals. So when a burglar (or cat) steps onto your driveway, it’s not the actual moving body that your PIR system spots - it’s an increase in infrared radiation. But the effect is the same, because it switches on the light and hopefully scares off the burglar (or the cat).