Question

For a radiation of 9 GHz passing through air. The number of waves passing through 1 m length is ____________.

Options

• 30

• 5

• 20

• 3

Answer 1

For a radiation of 9 GHz passing through air. The number of waves passing through 1 m length is 20.

Explanation:

v = 6 GHz = 6 x 10⁹ Hz

Velocity of radiation in air,

c =3 x 10⁸ m/s

`therefore lambda = "c"/"v" = (3 xx 10^8)/(6 xx 10^9) = 10^-1/2  "m"`

Wave number for the wavelength,

`"v"= 1/lambda`

∴ Here, number of waves in 1 m,

`"v" = "length"/lambda = 1/(10^-1/2) = 20`