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.

Kodak’s New Cameras Don't Just Take Photos—They Also Print Them

Your Instagram account wishes it had this clout.
Your Instagram account wishes it had this clout.
Kodak

Snapping a photo and immediately sharing it on social media is definitely convenient, but there’s still something so satisfying about having the printed photo—like you’re actually holding the memory in your hands. Kodak’s new STEP cameras now offer the best of both worlds.

As its name implies, the Kodak STEP Instant Print Digital Camera, available for $70 on Amazon, lets you take a picture and print it out on that very same device. Not only do you get to skip the irksome process of uploading photos to your computer and printing them on your bulky, non-portable printer (or worse yet, having to wait for your local pharmacy to print them for you), but you never need to bother with ink cartridges or toner, either. The Kodak STEP comes with special 2-inch-by-3-inch printing paper inlaid with color crystals that bring your image to life. There’s also an adhesive layer on the back, so you can easily stick your photos to laptop covers, scrapbooks, or whatever else could use a little adornment.

There's a 10-second self-timer, so you don't have to ask strangers to take your group photos.Kodak

For those of you who want to give your photos some added flair, you might like the Kodak STEP Touch, available for $130 from Amazon. It’s similar to the regular Kodak STEP, but the LCD touch screen allows you to edit your photos before you print them; you can also shoot short videos and even share your content straight to social media.

If you want to print photos from your smartphone gallery, there's the Kodak STEP Instant Mobile Photo Printer. This portable $80 printer connects to any iOS or Android device with Bluetooth capabilities and can print whatever photos you send to it.

The Kodak STEP Instant Mobile Photo Printer connects to an app that allows you to add filters and other effects to your photos. Kodak

All three Kodak STEP devices come with some of that magical printer paper, but you can order additional refills, too—a 20-sheet set costs $8 on Amazon.

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More Than 38,000 Pounds of Ground Beef Has Been Recalled

Beef-ware.
Beef-ware.
Angele J, Pexels

Your lettuce-based summer salads are safe for the moment, but there are other products you should be careful about using these days: Certain brands of hand sanitizer, for example, have been recalled for containing methanol. And as Real Simple reports, the U.S. Department of Agriculture’s Food Safety Inspection Service (FSIS) recently recalled 38,406 pounds of ground beef.

When JBS Food Canada ULC shipped the beef over the border from its plant in Alberta, Canada, it somehow skirted the import reinspection process, so FSIS never verified that it met U.S. food safety standards. In other words, we don’t know if there’s anything wrong with it—and no reports of illness have been tied to it so far—but eating unapproved beef is simply not worth the risk.

The beef entered the country on July 13 as raw, frozen, boneless head meat products, and Balter Meat Company processed it into 80-pound boxes of ground beef. It was sent to holding locations in Florida, Georgia, North Carolina, and South Carolina before heading to retailers that may not be specific to those four states. According to a press release, FSIS will post the list of retailers on its website after it confirms them.

In the meantime, it’s up to consumers to toss any ground beef with labels that match those here [PDF]. Keep an eye out for lot codes 2020A and 2030A, establishment number 11126, and use-or-freeze-by dates August 9 and August 10.

[h/t Real Simple]