What is the frequency (in MHZ) of a blue light whose wavelength is 4000 Angstroms?

Question

a.)75 b.)7500 c.)750,000 d.)75 million e.)750 million ????

Answer 1

4000 Angstroms = 4.0 * 10^-7 m = wavelength

Frequency = Speed of Light / Wavelength

f = (3.0*10^8 m/s)/(4.0*10^-7 m)
= 7.5 * 10^14 Hz
= 750 million MHz

The light spectrum is from 750,000 - 430,000 GHz. I think the poster above me made an error in the number of zeros. The speed of light would be 3.0*10^17 nanometers per second, not 10^14.

Answer 2

velocity = wavelength * frequency, so utilising algebra, frequency = velocity / wavelength. (approximating velocity of sunshine, so answer no longer precisely spectacular) velocity = 3 x 10^5 km/s. changing to meters: velocity = 3 x 10^8 m/s wavelength = 4000 Angstroms = 4000 x 10^-10 m So frequency = (3.0 x 10^8 m/s) / 4000 x 10^-10 m, = then you definately calculate the skill of 10, that's 8 - (-10) = 18, and placed the different words mutually: (3.0 / 4000) x 10^18 Hz = Cancel one thousand from the 4000 and 10^18: (3.0 / 4) x 10^15 Hz = 0.seventy 5 x 10^15 Hz = 7.5 x 10^14 Hz There are 10^6 Hz in one million MHz: 7.5 x 10^14 Hz * (one million MHz/10^6 Hz) = 7.5 x 10^8 MHz, very final answer

Answer 3

Speed of light = 3 x 10^8 m/s
OR 3 x 10^14 nanometers per second

4000 angstroms = 400 nanometers

So in one second, we divide the distance traveled by the wavelength distance to get frequency in hertz

3 x 10^8 / 400 = 7.5 x 10^11

which is 750 billion hertz.

Since we want the answer in megahertz, divide by 10^6 to get
7.5 x 10^5 megahertz, or 750,000 megahertz.
The answer is therefore (c).

Answer 4

4000 Angstroms = 4000 * 10^(–10) meters
frequency = c/wavelength
= (3 * 10^8) / (4000 * 10^(-10))
= 750million MHz