Question

1. circle each one with the longer wavelength.(3 pts)

a. microwaves or radio waves?
b. red light or green light?
c. infrared waves or red light?

1. circle each one with more energy.(3 pts)

a. violet light or red light?
b. orange light or blue light?
c. green light or yellow light?

Explanation:

Step1: Recall the electromagnetic spectrum and wavelength - frequency relationship

The electromagnetic spectrum (from longest to shortest wavelength): radio waves, microwaves, infrared, visible light (red, orange, yellow, green, blue, violet), ultraviolet, X - rays, gamma rays. Wavelength (\(\lambda\)) and frequency (\(f\)) are related by \(c = \lambda f\) (where \(c\) is the speed of light). Also, energy of a photon \(E=h f=\frac{hc}{\lambda}\) (where \(h\) is Planck's constant). Longer wavelength means lower frequency and lower energy.

For question 21:

a. Microwaves or radio waves

Radio waves have longer wavelengths than microwaves.

b. Red light or green light

In the visible spectrum, red light has a longer wavelength (\(\lambda_{red}\approx 620 - 750\space nm\)) than green light (\(\lambda_{green}\approx 495 - 570\space nm\))

c. Infrared waves or red light

Infrared waves (\(\lambda_{IR}\approx 700\space nm - 1\space mm\)) have longer wavelengths than red light (\(\lambda_{red}\approx 620 - 750\space nm\))

For question 22:

a. Violet light or red light

Since \(E = \frac{hc}{\lambda}\), violet light (\(\lambda_{violet}\approx 380 - 450\space nm\)) has a shorter wavelength than red light (\(\lambda_{red}\approx 620 - 750\space nm\)). Shorter wavelength means higher energy. So violet light has more energy.

b. Orange light or blue light

Orange light (\(\lambda_{orange}\approx 590 - 620\space nm\)) has a longer wavelength than blue light (\(\lambda_{blue}\approx 450 - 495\space nm\)). Blue light has more energy.

c. Green light or yellow light

Green light (\(\lambda_{green}\approx 495 - 570\space nm\)) has a shorter wavelength than yellow light (\(\lambda_{yellow}\approx 570 - 590\space nm\)). Green light has more energy.

Answer:

21.
a. Radio waves
b. Red light
c. Infrared waves

22.
a. Violet light
b. Blue light
c. Green light