Re: radio waves & electricity
Hello Disha,
Radio waves are electric power, so we already transmit electric power. The problem is nobody has perfected an efficient method to transport power through the air from one place to another in large quantities, even over short distances.
One way to do this is to make a narrow beam of RF energy that can be pointed at a distant receiving antenna.
To make a narrow beam antenna the antenna must be large, but not as physically measured in meters. It must be large in terms of wavelengths. A wavelength = c/f where c is the speed of light and f is frequency.
A narrow beam antenna would be at least 100 x 100 wavelengths.
Here are two cases:
At 15kHz a wavelength would be c/f = [3x10^8]/[15000] which is 20km so the antenna would be 2000km x 2000km for a 100 x 100 array which is impractical.
At 50GHz a wavelength would be c/f = [3x10^8]/[5x10^10] which is 6mm so the antenna would only be 600mm x 600mm but at 50GHz there are problems: it is not very efficient to produce very high frequency power, the atmospheric loss is very large at this high frequency, the beam is steered by the atmosphere, and other issues.
So, for now, a radio station transmits 50,000 or more watts of electricity in all directions. The energy is spread so thin we each receive 1/1,000,000 to 1/1,000,000,000 of it and then we must use a complicated receiver to amplify it up to a level where we can listen to the radio station.
hms