Some people are very concerned that radio wave power coming from radio transmitters’ antennas will harm people. In particular people are troubled by mobile phone masts causing long term health problems when they are near to their homes.
I just want to make it clear how much a transmitter’s power diminishes as it spreads out from a transmitter. I’m sure some feel it must follow a simple linear law such as:
- double the distance and get half the power,
- triple the distance and get a third of the power,
- quadruple the distance and get a quarter of the power.
When in fact it follows an inverse square law which is nonlinear and gives this type of result:
- double the distance and get a quarter of the power,
- triple the distance and get a ninth of the power,
- quadruple the distance and get a sixteenth of the power.
This means the power (and damaging energy) is much lower than might be expected at any particular distance. Even within a short distance the power can drop considerably.
Continue reading “Radio Wave Power And How It Gets Reduced By Distance”
At least one of my other posts How Distance Reduces The Power of Radio Waves (not yet published) requires an understanding of mathematical proportionality. In particular it requires an understanding of Inverse Proportion. So I have written this article to try and clarify it. It gives an explanation of the two types of proportion, otherwise known as variation, which are:
Continue reading “An Explanation of Direct And Inverse Proportion”
- Direct Proportion,
- Inverse Proportion otherwise known as Indirect Proportion.
Before demonstrating magnetic levitation this video shows a small magnet being cooled to a superconducting temperature using liquid nitrogen. Once cooled the superconducting magnet is shown levitating above a section of magnetic track as seen in the featured image.
Further in the video the magnet is kept longer at superconducting temperatures by building a container of liquid nitrogen around it. It is then seen being whizzed along by hand while levitating above, clinging to the side and hanging below, a Möbius strip track plastered in neodymium magnets.
Continue reading “Magnetic Levitation Using A Superconductor”
This post contains instructions on how to avoid spilling juice from cartons or Tetra Paks®, with a rectangular cross-section, while opening or lifting them. It’s quite natural to grip cartons by the easiest method (the broad sides) while opening them, or lifting them when they’re still full, causing the contents to pour or squirt out inadvertently. Cartons with a square cross section are indifferent to the sides that are gripped when lifting or pouring.
You go to the refrigerator and take out a new cool carton of juice. You hold it firmly and take off the seal and juice spurts out at you and runs down the side of the carton, or you pick it up after removing the seal and juice pours out as you grip it. Before you’ve got it in a glass you’re in a mess. This is usually caused by the way you grip the carton.
Continue reading “Spilling Juice From Cartons or ‘Tetra Paks®’”