How Does Wireless Charging Work—And Is It Safe?

iStock
iStock

by James Hunt

In 1899, the inventor Nikola Tesla began performing the first successful experiments on wireless power transfer. His initial success led him to believe that one day power would be transmitted around the planet without the need for cables. It took over 100 years, but his dream of wire-free power transmission was eventually realized—though perhaps not by the methods he envisioned.

When creating phones and tablets, manufacturers are faced with the challenge of giving the device a long battery life, keeping it lightweight, and making charging as painless as possible. Wireless power, which makes recharging your phone as easy as putting it down, could be the solution to that last part. But how does it actually work? And, perhaps more importantly, how safe is it?

Modern wireless power draws on the same principle that Tesla investigated over a century ago: induction. Electromagnetic induction—using an electromagnetic field to transfer power between two objects—forms the basis of all modern wireless charging, as well as things like contactless payment, cooktops, and wireless speakers.

In a practical sense, the way induction works is simple: First, you feed power to a base unit or charging station that contains a “transmitter” coil. An electromagnetic field forms around the transmitter and when a second “receiver” coil comes near enough, the receiver coil interacts with the magnetic field to create an electric current. By putting the second coil inside another device, you can wirelessly transfer power from the base to the device.

Most induction chargers only operate over a short distance, however, and while physical contact between a device and its base unit isn't necessary for induction to work, the fields generated lose so much power as the devices get farther away that it's usually the only way to get the two coils close enough.

As for safety, there's really nothing to worry about. The average induction charger creates a field no more dangerous than radio waves, and it isn't strong enough to have any effect on the human body. If anything, plugging in and unplugging a cable is more dangerous because there's a minute chance it could fray and shock you. By contrast, induction hardware can be safely encased in thick plastic and still work. This is why electric toothbrushes have long used induction to charge: The units can remain sealed and waterproof.

Sounds great, right? So why don't we use wireless charging all the time? For starters, it’s slow going. While wireless charging has improved dramatically over the past few years, wired charging is still generally faster. Also, the process creates a lot of waste heat, so much so that some Samsung charging pads have fans to keep everything cool.

The big issue is practicality, though. You can easily use your phone while it's plugged into a charger, but it's tricky to hold your phone up to your ear while it's resting on a wireless base station.

But things are changing.

Returning to Tesla's original experiments, an effect called Resonant Inductive Coupling allowed the inventor to safely transmit power over several meters. Perhaps the most popular wireless charging standard, Qi, has recently been updated to allow a version of this to be implemented in compatible devices. The result is that the charging range has increased to four centimeters.

It might not sound like much, but it's a start. In the future, wall-sized charge stations might be able to transmit power to multiple devices in multiple rooms as you move about your house. It may have taken over a century to get to this point, but we're closer than ever to wireless power transfer becoming commonplace. It's what Tesla would've wanted.

Friday’s Best Amazon Deals Include Digital Projectors, Ugly Christmas Sweaters, and Speakers

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Amazon
As a recurring feature, our team combs the web and shares some amazing Amazon deals we’ve turned up. Here’s what caught our eye today, December 4. Mental Floss has affiliate relationships with certain retailers, including Amazon, and may receive a small percentage of any sale. But we only get commission on items you buy and don’t return, so we’re only happy if you’re happy. Good luck deal hunting!

Google Is Tracking Everything You Do With Its ‘Smart’ Features—Here’s How to Make That Stop

Maybe you don't want Google seeing how many exclamation points you use in your emails.
Maybe you don't want Google seeing how many exclamation points you use in your emails.
Taryn Elliott, Pexels

Since we don’t all have personal assistants to draft emails and update our calendars, Google has tried to fill the void with ‘smart’ features across Gmail, Google Chat, and Google Meet. These automatic processes cover everything from email filtering and predictive text to notifications about upcoming bills and travel itineraries. But such personalized assistance requires a certain amount of personal data.

For example, to suggest email replies that match what you’d choose to write on your own—or remind you about important emails you’ve yet to reply to—Google needs to know quite a bit about how you write and what you consider important. And that involves tracking your actions when using Google services.

For some people, Google’s helpful hints might save enough time and energy to justify giving up full privacy. If you’re not one of them, here’s how to disable the ‘smart’ features.

As Simplemost explains, first open Gmail and click the gear icon (settings) in the upper right corner of the page. Select ‘See all settings,’ which should default to the ‘General’ tab. Next to ‘Smart Compose,’ ‘Smart Compose personalization,’ and ‘Smart Reply,’ choose the ‘Off’ options. Next to ‘Nudges,’ uncheck both boxes (which will stop suggestions about what emails you should answer or follow up on). Then, switch from the ‘General’ tab to ‘Inbox’ and scroll down to ‘Importance markers.’ Choose ‘No markers’ and ‘Don’t use my past actions to predict which messages are important.’

Seeing these settings might make you wonder what other information you’ve unwittingly given Google access to. Fortunately, there’s a pretty easy way to customize it. If you open the ‘Accounts’ tab (beside ‘Inbox’) and choose ‘Google Account settings,’ there’s an option to ‘Take the Privacy Checkup.’ That service will walk you through all the privacy settings, including activity tracking on Google sites, ad personalization, and more.

[h/t Simplemost]