921
Science Experiments / Re: What's your kitchen science?
« on: 05/10/2007 01:01:09 »
What you need
Small portable AM medium-wave / long-wave radio
Digital electronic gadgets (suggest TV remote control, MP3 player, digital watch or alarm clock)
What you do
Switch on the radio, and set it to MEDIUM WAVE or LONG WAVE.
This experiment will not work on VHF/FM.
Tune the radio to a quiet spot between any stations.
If you hear a lot of loud and nasty buzzes and whistles then ensure the radio is moved well away from any computers/consoles, and that nearby fluorescent lights and "energy-saver" lightbulbs are switched off.
Turn up the radio volume to maximum.
You may hear a little bit of hiss and some crackles or some feint whistles or foreign stations. That's okay. It's best to find the quietest position of the tuning that you can, however. The internal ferrite rod aerial is directional, so you can also try rotating the radio to make the background as quiet as possible.
Now place your TV remote control very close to the radio. Press a button on the remote.
Did it make you jump??!!
Now try pressing different buttons on the remote.
Now try placing other digital gadgets close to the radio, e.g. a (plastic-cased) digital watch, alarm clock, or an MP3 player.
You might find the effect is rather quieter (especially with the digital watch), so you may have to move the test-item around the case of the radio to find the most sensitive spot (which will be somewhere near the ferrite rod aerial inside).
With the watch or clock, you might find the sound changes as the seconds tick over.
With the MP3 player try playing a song, and skipping forwards or backwards tracks while listening to the radio.
Now for the really clever bit: place a mobile phone close to the radio. Start with the phone completely switched off, then switch it on while it's very close to the radio. After it's all settled down, try making a brief phone call (maybe to your balence enquiry/voicemail/or other free info service). Hang up. Again after it's settled down, try switching off the phone completely. There will probably be a mixture of very loud and much quieter subtle effects. You may have heard the loud ones in the past (you even get the loud ones on VHF/FM radios). Listen carefully even when the phone is switched on but apparently doing nothing (you may need to slowly and carefully move the phone around the case of the radio to find the best spot to hear this).
[I can explain what some of these are in a future posting]
This can be even more interesting to do if you're travelling longer distances (not driving) in a car or train and have a radio and phone with you. (It won't work with the car radio - you need a small portable/personal radio; earphones are fine). You don't need to make any calls - just leave the phone switched on and held next to the radio. You may have heard the loud sound on the FM band before too - but you need the medium/long wave band to hear some of the more subtle stuff. See what happens when you go into a tunnel or an area with poor mobile reception...
The radio is like a stethoscope diagnosis-tool for digital gadgets!
Small portable AM medium-wave / long-wave radio
Digital electronic gadgets (suggest TV remote control, MP3 player, digital watch or alarm clock)
What you do
Switch on the radio, and set it to MEDIUM WAVE or LONG WAVE.
This experiment will not work on VHF/FM.
Tune the radio to a quiet spot between any stations.
If you hear a lot of loud and nasty buzzes and whistles then ensure the radio is moved well away from any computers/consoles, and that nearby fluorescent lights and "energy-saver" lightbulbs are switched off.
Turn up the radio volume to maximum.
You may hear a little bit of hiss and some crackles or some feint whistles or foreign stations. That's okay. It's best to find the quietest position of the tuning that you can, however. The internal ferrite rod aerial is directional, so you can also try rotating the radio to make the background as quiet as possible.
Now place your TV remote control very close to the radio. Press a button on the remote.
Did it make you jump??!!
Now try pressing different buttons on the remote.
Now try placing other digital gadgets close to the radio, e.g. a (plastic-cased) digital watch, alarm clock, or an MP3 player.
You might find the effect is rather quieter (especially with the digital watch), so you may have to move the test-item around the case of the radio to find the most sensitive spot (which will be somewhere near the ferrite rod aerial inside).
With the watch or clock, you might find the sound changes as the seconds tick over.
With the MP3 player try playing a song, and skipping forwards or backwards tracks while listening to the radio.
Now for the really clever bit: place a mobile phone close to the radio. Start with the phone completely switched off, then switch it on while it's very close to the radio. After it's all settled down, try making a brief phone call (maybe to your balence enquiry/voicemail/or other free info service). Hang up. Again after it's settled down, try switching off the phone completely. There will probably be a mixture of very loud and much quieter subtle effects. You may have heard the loud ones in the past (you even get the loud ones on VHF/FM radios). Listen carefully even when the phone is switched on but apparently doing nothing (you may need to slowly and carefully move the phone around the case of the radio to find the best spot to hear this).
[I can explain what some of these are in a future posting]
This can be even more interesting to do if you're travelling longer distances (not driving) in a car or train and have a radio and phone with you. (It won't work with the car radio - you need a small portable/personal radio; earphones are fine). You don't need to make any calls - just leave the phone switched on and held next to the radio. You may have heard the loud sound on the FM band before too - but you need the medium/long wave band to hear some of the more subtle stuff. See what happens when you go into a tunnel or an area with poor mobile reception...
The radio is like a stethoscope diagnosis-tool for digital gadgets!