Wireless electricity. Just saying it still sounds a little like science fiction to me! And yet, more than a century ago, Nikola Tesla was already experimenting with the wireless transmission of electrical energy. If he wasn’t a time traveller, I’m not sure who could have been… [1]
Imagine ALL the electrical cables disappearing from our lives. Putting your phone on your desk and having it charge, parking your car and watching the same thing happen. And finally, no more trying to work out which of the fifteen chargers in the drawer is the right one!
How close have we come to that picture? Let’s first see how energy can travel without a cable connecting the two devices.
Tesla and a Very Big Dream
Tesla envisioned a worldwide system for transmitting energy and information wirelessly. The Wardenclyffe Tower in New York was part of that plan. The project, however, never became an operational global electricity supply system. The dream was enormous; its implementation remained unfinished. [1]
Even the thought still excites me. Looking at a world full of wires and asking: “What if we could do this differently?”
How Does Wireless Electricity Work?
Let’s revisit electromagnetic induction. When the magnetic flux through a coil changes, it induces a voltage. If the circuit is closed, a current can flow. This is the basic idea behind Faraday’s law. The coil itself does not even need to move: a changing magnetic field is enough. [2]
An inductive charging system has two coils. Alternating current in the transmitter coil produces a changing magnetic field, which induces a voltage in the receiver coil. This transfers energy that can be used to charge a battery. [3]
So the cable between the charger and the device can disappear. The charger itself, of course, still needs a power supply!
Where Does Resonance Come In?
Two electrical circuits designed to resonate at the same frequency can exchange energy efficiently when suitably coupled through their magnetic fields. Here, resonance refers to the circuits; a shared frequency alone does not guarantee good power transfer at any distance. [4]
In 2007, an MIT team provided a lovely example: it lit a 60-watt bulb from more than two metres away using magnetically coupled resonators. There was no wired connection between the source and the bulb. Two metres might sound modest, until you imagine that bulb glowing in front of you! [4]
From Phones to Cars — and Further Still
Wireless charging has already found a place in our everyday lives. Qi chargers use magnetic induction, while the phone communicates with the charging base to control the power supply. Quite a lot happens behind that simple act of putting your phone down to charge. [5]
Research is also moving towards much higher power levels. In March 2024, Oak Ridge National Laboratory announced a demonstration transferring 100 kW wirelessly to a Hyundai Kona electric vehicle across an air gap of about 13 centimetres. This was a research demonstration integrated into a vehicle, showing the technology’s potential beyond small devices. [6]
Other methods are being explored for longer distances. In May 2025, DARPA announced a demonstration delivering more than 800 watts over 8.6 kilometres for 30 seconds using a laser. A specialised receiver with photovoltaic cells converted the light into electrical energy. Here, power travels in a directed light beam, with different requirements from those of a phone’s charging pad. [7]
Pretty impressive for an idea that still feels like a scene from a film to me!
Will We Say Goodbye to Every Cable?
In inductive power transfer, the distance, size and alignment of the coils affect coupling and efficiency. How much energy actually reaches the device matters just as much as whether we can transfer it wirelessly. [3]
Charging a phone on a pad is, after all, a long way from powering an entire city without wires. Every step, though, gives our imagination a little more room.
Personally, I’m still imagining a desk without tangled chargers. And if Tesla could see these experiments, I would love to hear what he had to say.
Until then, let’s see what will change!
Change is the only constant.
Read also: Planck’s Constant — ℏ
Sources
- Tesla Science Center at Wardenclyffe — Tesla’s Wireless Power
- OpenStax, University Physics Volume 2 — Faraday’s Law
- Wireless Power Consortium — Principle of Inductive Power
- MIT News — Goodbye wires! (7 June 2007)
- Wireless Power Consortium — How Qi Works
- Oak Ridge National Laboratory — Charging up the commute (12 March 2024)
- DARPA — DARPA program sets distance record for power beaming (16 May 2025)
