Physics frequency order http://upload.lsforum.net/users/public/w349222t72.png?

Frequency of,
- 5 GHz radar = 5 x 10^9 Hz

- 3 micron infrared radiation = 3 x 10^8/3 x 10^-6 Hz = 10^14 Hz
[where 3 x 10^8 m/s is the speed of light ]

- 20 kHz sonar = 20 x 10^3 Hz = 2 x 10^4 Hz

- 4 kHz of sound = 4 x 10^3 Hz

- blue light = 3 x 10^8/450 x 10^-9 Hz = 6.67 x 10^14 Hz
[ Take the wavelength of blue light be 450 nm]

- 2000m radio = 3 x 10^8/2000 Hz = 150 kHz = 1.5 x 10^5 Hz

Therefore, the frequencies in ascending order is:
4 kHz sound ( 4 x 10^3 Hz)
20 kHz sonar ( 2 x 10^4 Hz)
2000m radio ( 1.5 x 10^5 Hz)
5 GHz radar ( 5 x 10^9 Hz)
3 micron infrared ( 10^14 Hz)
blue light ( 6.67 x 10^14 Hz)