Radio Definition and 671 Threads

Pandora Radio is an automated music recommendation service and custodian of the Music Genome Project. Users enter a song or artist that they enjoy, and the service responds by playing selections that are musically similar. Pandora service is not available outside USA. I didn't know that any...

Because they don't have enough energy to be noticed? If I understand right, they are not energized enough to ecxite electrons?

Hi community. Once again, a stupid question: if radio waves are electromagneetic waves, generating an electric field in the antenna, then why can't one just shine visual light (also electrromagnetic waves) on same antenna and use that for communication? thanks s

I work in wildlife science. I track radio tagged animals, and am wondering if it's possible to make a radio wave camera, that can detect and visualize radio waves on a screen. I could use this camera to see the source of a radio signal (i.e. which bush or tree an animal is hiding in). This...

Ok this does come from the movie "Contact" with jodie foster. Where she mintors space for aliens transmitting radio signals. I am sure lots of you have seen it :) Now my question is, can you buy a certain type of radio(amateur), and scan millions of frequencies to search for alien radio...

Homework Statement Pulsed lasers used for science and medicine produce very brief bursts of electromagnetic energy. If the laser light wavelength is 532 nm, and the pulse lasts for 37 ps, (a) how many wavelengths are found within the laser pulse? (b) How brief would the pulse need to be to...

I know that chemical reactions can emit light and heat, and these are part of the electromagnetic spectrum. But are there any chemical reactions that can directly produce electromagnetic emissions in the radio part of the spectrum?

i want to create my own radio transmitter and receivers and i don't want to use printed circuit boards or some kits .can any please provide details

hi this has been buggin my for a few days now, I've got a T Reg Vauxhall Vectra Diesel, a few days ago my battery went completely kapput so sorted that problem out, got in the car and noticed that my CD player is now asking for an unlock code >.<, i went to my local garage and they want £25 just...

Hi, I've been mulling over an idea (you know how it is, just to keep the grey matter ticking) on how to build a device for tracking...well anything... from hunting dogs to humans. The device would include a GPS (lat, long, altitude, vert & horz accuracy, UTC time) to give bearing over time...

I am simulating a trilateration process that does not require accurate timings to be transmitted as data. The trilateration process uses a known power density, at the transmission source, to within a fine tolerance. Thus, the following equation is the basis for the calculation: Power...

Hi! I need help with the method to approach a question, if I wish to calculate how long it will take for a radio message to reach a certain planet (just the general concept), what will be the key pieces of information I require? I know I need: the distance from Earth to said planet the...

Good Morning Can anyone help me understand why, apparently the physical length of a monopole end feed wire for a crystal set need to be ½ the wave length of the desired signal. The reason I ask is, that I understood that, if you have a variable coil in series with the antenna, the...

If infared radiation is responsible for somethings heat, why do microwaves use radio waves?

I’ve heard that the reason radio telescope dishes can be made out of wire mesh is because, so long as the size of the holes is less than (I believe) 1/10 the wavelength of the radio wave, the wave be reflected (it will see the dish as being solid). I was wondering what the physical reason was...

Are human beings radio wave transmitters? I recently moved to a new town and started listening to a new station on 101.9 fm. Found their broadcast plagued by static interference. Tried all the usual suspects, but it really looks like I am the source. When I approach the tuner the static...

Hey guys, been trying to Google tons of things but am striking out. I'm curious how the process of sending and receiving radio waves works. What I'm looking for, more specifically, is how do you send specific wavelengths and amplitudes and then once those waves are airborne, how do you create...

what has "radio" got to do with this activity? Probably sounds silly, but what has "radio" got to do with this activity? I don't know if I'm interpreting this guy's formula right (http://www.hps.org/publicinformation/ate/q8270.html) so can someone confirm this expression for half life: A=...

(Sorry if this is off-topic for this group. There's really no group that addresses accelerators in the Physics Forums) I've looked at many examples of RFQ linear accelerators. Most of them share the same characteristics: 1. So-called vane electrodes 2. Opposite-facing electrodes...

i was trying to look for which forum to put this in so sorry if its in the wrong one. :D Im working on a project and i need a material that is able to reflect radio waves, like a mirror reflects light. any ideas for which material will reflect?

Homework Statement in a certain uhf radio wave, the shortest distance between postions at which the elctric an magnetic fields are zero is .34m. determine the frequency of this uhf radio wave The Attempt at a Solution i basically just divided (3x10^8)/.34 = (8.8x10^8) that is...

I just noticed that we tend to call EM wavelengths shorter than visible light "rays" while we call we call those that are longer "waves". Why is that? Did we ever think that "rays" and "waves" were physically different?

it has been a while. i need to know which wavelength is bigger FM radio or Am radio?

Hi Everybody! I have been wondering about wave generation from point sources, and interference. I have noticed that if several point sources are sited in a line much more than one wavelength long, a very directional interference pattern develops. The closer the sources and the longer the line...

Homework Statement An AM station is broadcasting a radio wave whose frequency is 1400 kHz. The value of the capacitance in Figure 24.5 is 8.4 X10 -11 F. The Value of the capacitance in Figure 24.4 is 8.4X10-11 F. What must be the value of the inductance in order that this station can be tuned...

Why do electronic devices such as calculators and tv remotes send frequencies that can be picked up on am radios?

So, I've heard it said that when you use a hand-held radio, your body acts as a ground. Let's say I wanted to go on an adventure with my homemade flying machine (lawn chair and weather balloons). Obviously, my friends would like to know how the world looks and feels from that height. I choose...

I'm having to do a project and i got to do a detailed presentation describing and explaining the basic physics principals for gps's, tv's and radio. Each section has to be around 3-4 minutes of explanation. Im hitting a big rut with trying to find research for it. Also I am in gr.12 physics...

Just curious, what is the longest wavelength we can currently observe with our instruments, & are there are good sources for future (even if just theoretical) projects at longer wavelengths (future projects do no have to be based on Earth)?

When radio waves go through certain walls , I was reading about this , do they go through the wall because their wavelength is too long to interact with the matter in the wall , Does it haft to do with the crystal spacing in the matter , and in some cases is it like light going through...

Evolution is the greatest nano-engineer that ever existed. I always assumed that if anything was physically possible at everyday Earth temperatures, forces and velocities then it would have emerged naturally from evolution, since the evolutionary benefits are clearly enormous. eg that's why...

Homework Statement The car is approaching a radio station at 25m/s. Broadcast frequency is 74.5 MHz. What change in frequency does the driver observe. Homework Equations Doppler effect on EM waves Fo = Fs (1 (+/-) u/c) u = speed of observer c = speed of light The Attempt at a Solution...

Homework Statement A spaceship leaves Earth at 12 noon. At that time the spaceship clock is set to be synchronised with Earth time. It travels through space in a straight line at a constant speed 0⋅60 c. A radio signal is sent to the spaceship from Earth at 2pm. A shuttle is launched from...

I would like to measure the distance between team players in the field. I need a device that can signalize when a distance between 2 players of the same team approaching a certain distance (2, 3 or 4 meters). The device must be relatively small (in order to have in on a players), to...

Pretty moving radio piece from NPR - My Lobotomy. It lasts about 23 minutes. When Howard Dully was 12 years old, his stepmother didn't like having him around. After shopping for child psychologists and having at least four of them insult her by suggesting that maybe she was the one that...

First of all, new to the forums, so HELLO! I am currently working on a project and cannot catch a break on what I need to be looking for. The project consists of calibrating antennas based on the radio noise from the Milky Way. We would like to point the antenna at the center of the milky way...

Sorry if I posted this in the wrong location, it seemed like the most appropriate board. Homework Statement As you drive down the highway, you notice that the dial on your stereo is not functioning. You have the radio tuned to a station that uses two transmission towers that are 175.0 m...

Homework Statement Typical AM radio waves usually have a frequency between 540 kHz and 1400 kHz. FM radio waves tend to have frequencies between 89 MHz and 105 MHz. Both types of waves travel at the speed of light. In terms of diffraction, use this information to help explain why in many low...

Homework Statement At a distance of 25m from an isotropic 100 MHz radio source the intensity is 120W/m2. A) What is the rms electric field at 25m? The answer should be 213 V/m. B) Over a 2 hour period, what is the momentum given to a 4cm x 4cm surface (at the 25m distance)...

Hello, I've been puzzling over how radio waves and other EMR are formed at the subatomic level. I understand how to produce radio waves using a function generator but I do not understand how an antenna can emit a radio wave (among other types of EMR). I've asked several people this, but all...

Hi folks, EM radio signals range in frequencies from a couple Hz up to approximately EHF (30-300GHz)... As we exceed the 300GHz threshold, we begin to approach the infrared section of EM spectrum, and furthermore into the visible light area of the spectrum. My question is, what happens...

Hello folks. I want to buy a powerfull Fm Transmitter kit. Where can i find one at reasonable price? Cheers..

Homework Statement I bought an FM radio mono kit. After I assembled it, it works. But I want to know how to have a clear reception or signal and to acquire more stations. What should I do? Any tips or techniques? does the coil affects the signal? Homework Equations The Attempt at a...

Hello All, For a hobby, my father, friend, and I are building a radio controlled tank. Without getting into to much ancillory info, the problem we are facing appears to be radio frequency interference. Using a radio control transmitter, we are sending a signal to the receiver. That...

Homework Statement Build an AM/FM radio. Determine the frequency and wavelength of the radio wave for best reception. 2. The attempt at a solution I have built a AM/FM radio. My only problem is how do I determine the optimum frequency for best reception? I have only one solution and...

For an engineering project I am trying to place a 2.4GHz RFID tag inside a resin casting of a large seaside pebble. However since the resin is less dense than a real pebble, I need to add some mass of metal (since is is much denser) to the resin before it sets. It is crucial for the casting to...

photon refers to radio waves or not? the definition of photon refers the photon as the quantum of the electromagnetic field , however on the courses of physics(high school) when i said that, the teacher claimed that I'm wrong and photon refers only to visible light. who was wrong and why?thank you.

Hi there... I have a question regarding satellite. If I am posting in the wrong place, I'm very sorry (in advance :blushing:) Here's my question. Why is a satellite dish for TV (think Dish Network) so much bigger than one for satellite radio? Sure would be more attractive to have a teeny...

Homework Statement How Can you use triode as detector in radio wave receivers?Homework Equations N/AThe Attempt at a Solution when the radio receivers were invented , triode was used to detect them but what function enables this is our of my mind!

Say I make a simple crystal radio using a 1N34A diode. If I use it to tune in a radio station 100 miles away, would it be possible in theory to detect an infinitesimal increased load at the station when I tune it in with my crystal set?