## Wednesday, March 01, 2017

### Lenz's Law Is A "Quirk" Of Physics?

I've never heard of "fidget toys" before till after I read this piece. This one is describing a fidget toy that supposedly has "antigravity" effects that simulates the low gravitational field of the moon and Mars, making the object falls slower. The toy is called Moondrop.

Based around the principle of Lenz’s law — which *deep breath* states that the current induced in a circuit due to a change or motion in a magnetic field will create a field that opposes the charge that produced it — Moondrop is a gravity-defying fidget desk toy that imitates the differential gravitational free fall on Mars and the Moon.

OK, so immediately, there are two issues here:

1. Lenz's law is not a "quirk" of physics, as stated in the title of this report. In fact, it is quite a central phenomenon in physics that is responsible for power generators to create our household electricity! So how is that a "quirk"?

2. Any physics undergraduate can spot the error in the definition given for Lenz's law. Lenz's law is the effect whereby a magnetic field is generated to oppose the CHANGE in the external magnetic field. Maybe there is a typo in the definition given, that it should have been "change" instead of "charge". That one word (or in this case, one letter) change results in an astounding difference in the physics.

If I recall correctly, there are magnetic breaks that use the same principle. I remember reading something on roller coaster rides that made use of such magnetic breaks, so that it ensure that the vehicle can still be safely stopped even when the power goes off.

So the application of Lenz's law is neither that highly unusual, nor is it a quirk of physics.

Or maybe the writer meant a "quark" of physics?

Zz.