What is the best way to block/ trap phone radiation?
NO electronics emit any harmful radiation! How would they? What is the radioactive source? They do give off electromagnetic radiation, but that is just a fancy way of saying "magnetic field." Every electronic device in the world give off this. Even your car, which you drive everyday. We live in a huge electromagnetic field produced by the earth. Cell phones use a mechanism similar to radio waves, but that is not harmful either. I'm tired of everyone thinking electronics give off harmful radiation. They don't!!!! Electromagnetic radiation (magnetism), thermal radiation (heat), even light and radio waves are a form of safe radiation. Just because something is called "radiation, that doesnt mean it's harmful.
Can lead block UV-radiation?
Indeed, lead can easily block UV. It is typically used to block x-rays which are an even higher energy electromagnetic radiation. Glass (silicon) can typically block infra-red and allow UV to pass.
Does water block radiation?
Yes. Even light!There are very many kinds of radiation, and there are a lot of differences in how well water will stop them. The easiest way for physicists to describe that is by naming the thickness of the layer you need to stop roughly 63%, so that 1/e = 1/2.71828... = roughly 37% passes through. If you stack 10x that amount, only 0.004% comes through. Another way to express it is the "absorbance", which is one divided by that characteristic thickness.Let's start with the electromagnetic spectrum. There is a whole Wikipedia article about this that shows an excellent graph. In that graph you can see that the only electromagnetic radiation that can really pass through large thickness of water is visible light. Half of all blue/green light will pass through 50 meters of water. Half of red light through 20 meters. If you move into the ultraviolet, the absorbance really goes very high to [math]10^8[/math], which means you quickly need only 0.01 micrometer of water to stop 63% of that radiation. For even shorter wavelengths, the penetration increases a little and you need thicker layers. On the infrared absorption is more variable and a little less strong: you need several micrometers up to almost a millimeter of water to stop 63% there. And the thickness comes to roughly a cm if you go all the way to microwaves.See: Electromagnetic absorption by waterFor alpha radiation and beta radiation, water is an excellent shield and you need a thin sheet. Neutron radiation is a bit more hard, you need thick layers to stop it all, but water is one of the best materials to do that.See also: Radiation protection (this mentions also more exotic radiation)And: Shielding of Neutron Radiation
Is there radiation that can pass through Lead?
Absolutely. Cosmic radiation does so readily. High-energy gamma will also pass through a reasonable amount of lead.
What materials block or refract radio waves?
Radio waves are a type of electromagnetic radiation, a kind of energy that also includes visible light. Radio waves are not harmful but are in fact extremely useful for communicating across long distances. To send information using radio waves, a transmitting antenna sends out a radio wave at a certain frequency (which can tell us the size of the wave), and this is picked up by a receiving antenna. Some materials can block, or interfere with, radio waves. Have you ever noticed that you lose reception on a car radio or cell phone when you drive into a tunnel or an underground parking garage? What materials block the radio waves, and which ones allow the waves to easily pass through?Radio waves can be blocked (reflected) or attenuated (partially reflected or absorbed) by anything that conducts electricity. A thin sheet of aluminum can completely block (reflect) radio waves. They simply cannot penetrate it. Salt water (as in the ocean) permits radio waves to penetrate only a very short distance. In the same way, living plant material contains water and dissolved ions (the plant's "blood" or the plants food). This makes the plant something of a "conductor" of electricity. When radio waves (electromagnetic energy) come across a conductor, the frequency of the radio waves, their amplitude, and the "nature" of the conductor will result in a varying degree of interaction. The radio waves induce micro currents within the conductive material (the foil, the salt water, the plant with its moisture and ions, whatever). This interaction reflects or absorbs the energy (to a greater or lesser degree) of the incoming radio wave.
Why does lead block radiation when lead had originally decayed from uranium?
I don't understand how or why something that emitted radiation could stop emitting and start blocking the same radiation it emitted in the first place. Hope that made sense. :)
Does aluminium block radiations?
I’m going to assume you are talking about nuclear/ionizing radiation, rather than light, radio waves, infrared, etc.So, for starters, ALL MATTER blocks radiation to some extent. The thicker the material, and, in general, the denser it is, the more effectively it blocks it. For neutrons, there’s a property of the material (its neutron capture cross-section) that is very important to its ability to block (absorb) neutrons and is unrelated to density, so thin layer of boron is more effective than a thick layer of lead, but for alpha and beta particles and gamma rays, density plays the major role. These lose energy as they pass through a substance by interacting with the electrons and/or nuclei of the substance, and losing energy in the process. Generally, alpha and beta particles are easy to stop completely, they won’t go far into any solid substance. Gammas (and x-rays) are more penetrating, and instead of being stopped cold by some specific thickness, they are gradually attenuated: if you have a thickness that absorbs half the gamma energy, twice that thickness will absorb 3/4, triple the original thickness absorbs 7/8, and so on.Back to aluminum. Being not very dense, aluminum is not a good shield for gamma rays: it would generally require a very thick layer of aluminum to absorb them. OTOH, even thin aluminum foil will stop alpha particles. And something interesting turns up when you compare aluminum and lead as shielding for beta particles. A dense metal like lead stops betas very fast. A lighter metal like aluminum stops them more gradually; the beta particles penetrate further into the metal, losing a bit of energy with each collision and eventually coming to a stop. Well, it turns out that if you stop a fast electron (which is what a beta particle is) very abruptly, some of its kinetic energy is converted into x-rays, a process called Bremsstrahlung (braking radiation). So if you use lead to stop beta particles, you get x-rays that require even more lead to stop them. If you use aluminum, you get very little Bremsstrahlung because the electrons stop more slowly. So aluminum (or just plastic) is a preferred radiation shield when working with high-energy betas.
What can I use to block high frequency microwave radiation?
There is a shielding process used for this purpose .Electromagnetic shielding is the practice of reducing the electromagnetic field in a space by blocking the field with barriers made of CONDUCTIVE or magnetic materials. Shielding is typically applied to enclosures to isolate electrical devices from the 'outside world', and to cables to isolate wires from the environment through which the cable runs. Electromagnetic shielding that blocks RF electromagnetic radiation is also known as RF shieldingTypical materials used for electromagnetic shielding include sheet metal, metal screen, and metal foam. Any holes in the shield or mesh must be significantly smaller than the wavelength of the radiation that is being kept out, or the enclosure will not effectively approximate an unbroken conducting surface.Another commonly used shielding method, especially with electronic goods housed in plastic enclosures, is to coat the inside of the enclosure with a metallic ink or similar material. The ink consists of a carrier material loaded with a suitable metal, typically copper or nickel, in the form of very small particulates. It is sprayed on to the enclosure and, once dry, produces a continuous conductive layer of metal, which can be electrically connected to the chassis ground of the equipment, thus providing effective shielding.RF shielding enclosures filter a range of frequencies for specific conditions. Cu is used for RF shielding because it absorbs radio and magnetic waves. Properly designed and constructed copper rf shielding enclosures satisfy most RF shielding needs, from computer and electrical switching rooms to hospital CAT-scan and MRI in hospitals .
What material is resistant or blocks radiation?
Not to be flippant, but all material will resist radiation... if you have enough of it. It also depend of the types of radiation you're shielding from. Alpha particles are basically helium nuclei without electrons, and most don't make it past you skin, as they collide with the skin's molecular structures. Beta particles travel a little further, a few inches under the skin, and can kill small animals, but not larger ones. Gamma radiation is an electro magnetic wave, like radio or light, and is incredibly high energy. It will travel through voids in any material until it hits something and alters it permanently. These are the one's to worry about! Traditionally, lead is the metal of choice for shielding against harmful radiation. If you've ever had Xrays at the doctor's office, they put that big heavy drape over your "stomach" to protect you from the radiation. And that lead shield is 1 centimeter thick, and they weigh a lot! A shield like that around your house would be so heavy, the house would collapse. Water can also shield you from radiation, if you go deep enough. Paper and other insulators shield you from infrared radiation and heat. Gold too can block radiation, but it's way too expensive. What it usually boils down to it weight and density. The denser something is, the more it will block, shield, or absorb radiation. A half inch of lead will stop almost all forms of radiation, but is so incredible heavy, it would fail in most construction applications. A lead foil would be too thin to stop most the harmful particles and rays.
Why can't you use lead to shield radio waves?
In the strictest sense, magnetic shielding is not truly shielding at all. Unlike the way a lead shield stops X-rays, magnetic shielding materials create an area of lower magnetic field in their vicinity by attracting the magnetic field lines to themselves. The physical property which allows them to do this is called "permeability".Unlike X-rays, sound, light or bullets, magnetic field lines must travel from the North pole of the source and return to the South pole. Under usual circumstances, they will travel through air, which by definition has a permeability of "1". But if a material with a higher permeability is nearby, the magnetic field lines, efficient creatures that they are, will travel the path of least resistance (through the higher permeability material), leaving fewer magnetic fields in the surrounding air.Now it is easier to see why a magnetic shield in the shape of an enclosure (sphere, box, tube, etc.) offers much better shielding than a flat shape or partial enclosure. A source within the shield will produce field lines which will travel through the air immediately surrounding the North pole until they reach the shield. Then traveling through the shield, they will emerge into the air surrounding the South pole and back to the source. Traveling through the low permeability air outside the shield does not offer any efficiency advantage! (Notice that the diagram to the right is a cut-away view of a tube shaped shield.)Similarly, if the source of the field is outside of the enclosure, the magnetic field lines will travel through the material of the enclosure on their way back to the source, never finding it more efficient to permeate the air space inside the enclosure. For these reasons, enclosing either the source of the field, or the thing(s) that you wish to protect from the field, offers the most effective use of the shielding material, and is usually the most cost efficient as well!