Use the answer space provided to arrange the letters for the following electromagnetic radiation sources in
order of increasing frequency. (10 points – 2 points each)
a. A red traffic light at 700 nm.
b. The frequency for WZLX, transmitting FM radio waves at 100.7 MHz on the radio dial.
c. Ultraviolet light at 345 nm that is blocked by “Sun Block” to prevent your skin from burning from
exposure to the sun.
d. A green LED light with a wavelength of 555 nm.
e. An infrared heat lamp emitting at a frequency of 3 × 1013 Hz.
Answer: ________ < ________ < ________ < ________ < ________
To arrange the electromagnetic radiation sources in order of increasing frequency, we need to understand that frequency is inversely proportional to wavelength. This means that as the wavelength increases, the frequency decreases and vice versa.
Let's analyze each source of radiation and determine their frequencies:
a. A red traffic light at 700 nm:
To find the frequency, we can use the equation: c = λν
where c is the speed of light (approximately 3 x 10^8 m/s), λ is the wavelength in meters, and ν is the frequency in Hz.
Converting the wavelength of the red traffic light from nanometers to meters:
700 nm = 700 x 10^-9 m
Plugging the values into the equation:
c = λν
3 x 10^8 m/s = (700 x 10^-9 m) ν
Solving for ν:
ν = (3 x 10^8 m/s) / (700 x 10^-9 m)
ν ≈ 4.29 x 10^14 Hz
b. The frequency for WZLX, transmitting FM radio waves at 100.7 MHz on the radio dial:
MHz stands for megahertz, which is 10^6 Hz. So we can directly convert the frequency to Hz:
100.7 MHz = 100.7 x 10^6 Hz
c. Ultraviolet light at 345 nm that is blocked by "Sun Block":
Following the same process as in part a:
345 nm = 345 x 10^-9 m
Using the equation:
c = λν
3 x 10^8 m/s = (345 x 10^-9 m) ν
Solving for ν:
ν = (3 x 10^8 m/s) / (345 x 10^-9 m)
ν ≈ 8.70 x 10^14 Hz
d. A green LED light with a wavelength of 555 nm:
Following the same steps as in part a:
555 nm = 555 x 10^-9 m
Using the equation:
c = λν
3 x 10^8 m/s = (555 x 10^-9 m) ν
Solving for ν:
ν = (3 x 10^8 m/s) / (555 x 10^-9 m)
ν ≈ 5.41 x 10^14 Hz
e. An infrared heat lamp emitting at a frequency of 3 x 10^13 Hz:
No additional calculations are needed as the frequency is already provided in Hz.
Now, arranging the sources in order of increasing frequency:
Answer: 4.29 x 10^14 Hz < 5.41 x 10^14 Hz < 8.70 x 10^14 Hz < 3 x 10^13 Hz < 100.7 x 10^6 Hz