Practice portal › Electromagnetic Waves › Uses of the Bands, and lambda nu = c

For a radiation of 9 GHz passing through air, the number of waves passing through 1 m length is

Asked in GUJCET 2017 · Wavelength, frequency and photon energy

• (1) 30
• (2) 5
• (3) 20
• (4) 3

Step-by-step solution

Why the other options are wrong

• (2) comes from no single slip produces 5. Sanity check: one wave occupies λ=c/u=1/(30) m, so 30 of them fit into a metre.
• (3) 20 is the count for a 6 GHz radiation, not a 9 GHz one; a lower frequency means longer waves and fewer of them per metre.
• (4) comes from writing c=3×10⁹ m s⁻¹ instead of 3×10⁸: (9×10⁹)/(3×10⁹)=3.

Reading this solution needs no sign-in. You only sign in to practise against the clock and keep your progress.