Question

question 9 of 30
which type of electromagnetic wave has less energy than an infrared wave?
a. gamma ray
b. ultraviolet wave
c. visible light
d. microwave

Explanation:

To determine which electromagnetic wave has less energy than an infrared wave, we use the relationship between energy, frequency, and wavelength of electromagnetic waves: \( E = hf=\frac{hc}{\lambda} \) (where \( E \) is energy, \( h \) is Planck's constant, \( f \) is frequency, \( c \) is the speed of light, and \( \lambda \) is wavelength). Energy is directly proportional to frequency and inversely proportional to wavelength. The electromagnetic spectrum in order of decreasing wavelength (and thus decreasing energy, since energy and wavelength are inversely related) is: radio waves, microwaves, infrared, visible light, ultraviolet, X - rays, gamma rays.

• Option A: Gamma rays have a very short wavelength and high frequency, so they have more energy than infrared waves.
• Option B: Ultraviolet waves have a shorter wavelength and higher frequency than infrared waves, so they have more energy than infrared waves.
• Option C: Visible light has a shorter wavelength and higher frequency than infrared waves, so it has more energy than infrared waves.
• Option D: Microwaves have a longer wavelength than infrared waves. Since energy is inversely proportional to wavelength, microwaves have less energy than infrared waves.

Answer:

D. Microwave