**Frequencies**

Electric
current is basically two types, Alternating Current denoted as AC and Direct
current DC. One of the main parameter of AC is the frequencies. The variation of current or voltage from
zero, to a maximum positive point then again it come back to the zero and move
to maximum negative point, and back to zero, is termed as “cycle” .

The
number of cycle traversed by current or voltage in one second is known as its
frequency. In other words number of cycles repeated in one second is called
cycle per second or frequency.

Frequency
is measured as hertz. If an ac cycle is
completed in one second that frequency is called one hertz.

1000 Hz =
1KHZ (KiloHertz)

1000KHZ =
1MHZ (MegaHertz)

1000, 000 =1 GHZ (GigaHertz)

Frequency’s are classified as
below as some special properties exhibited by them.

10 Hz - 30 Hz Very
Low Frequencies (VLF)

30Hz – 300 Hz Low
Frequencies (LF)

300 Hz -3 MHZ Medium
Frequencies (MF)

3 MHZ -30 MHZ High
Frequencies (HF)

30 MHZ - 300 MHZ Very
High Frequency (VHF)

300 MHZ – 3000 MHZ Ultra
High Frequency (UHF)

3000 MHZ – 30,000 MHZ Super High
Frequency (SHF)

Electricity is travel at the
speed of light, depends on the conductor there is some variations.

That means velocity of Ac 3 x
10^{8} so the distance travelled
by an alternating wave is called Wave
length ( it is denoted by “ λ” Lamda).

The Wave Length λ = (Speed of
light / Frequency) that is (3x10^{8}/F)