Question

The radio waves that travel through the air to our car/truck/home radios are just another type of light. Let's say that your favorite radio station is 87.9 on the FM dial. That means that those radio waves have a frequency of 87.9 MHz. (a) What are the wavelength and energy of those radio waves? (b) How fast would these radio waves travel through water?

Answer 1

Step-by-step explanation:

(a) Electromagnetic waves travels at the speed of light = 3.0 x
`10^(8)` m/s.

v = fλ

where v is the velocity of the wave, f is the frequency, and λ wavelength.

So that;

λ =
`(v)/(f)`

=
`(3.0*10^(8) )/(87.9*10^(6) )`

= 3.413 m

ii. Enegy of the wave can be determined by;

E = hf

where h is the Planck's constant and f the frequency of the wave.

E = 6.626 x
`10^(-34)` x 87.9 x
`10^(6)`

= 5.82 x
`10^(-26)` J

(b) Refractive index of water =
`(velocity of light in air)/(velocity of light in water)`

velocity of light in water = 1.33 x 3.0 x
`10^(8)`

= 3.99 x
`10^(8)` m/s